Autocross is a form of motorsport involving a driver maneuvering a car over a closed course, one at a time, against the clock, with the goal of completing the course, without incurring any penalties, and in the shortest time.
Autocross events are typically held on a large parking lot, with a course marked with cones. Hitting a cone incurs a penalty (normally adding two seconds per cone to the competitor's time). Deviating from the marked course incurs a penalty of disqualifying that particular run time (DNF or Did Not Finish). Autocross differs from Gymkhana in that an Autocross course is usually more like a miniature road course, which does not cross over itself, and is marked in such a way that the driver can follow the intended path without memorizing a course map. Course length is normally desired to be long enough that it takes one minute to complete, and course layout is intended to keep vehicle speed below 60 MPH.
Autocross emphasizes the driver's control of the car and the car's handling ability over raw horsepower. For this reason, Autocross has long been a popular motorsport for small displacement cars, especially sporty front wheel drive cars like the Geo Storm and its Isuzu sister cars. These cars have a reputation for good handling and peppy performance, and chances are better than average that if you take one to an autocross event, an experienced racer will comment that they used to have one, and wish they still had it.

Cars are divided into different groups, purportedly of comparable ability, and often including an ascending scale of allowable modifications in order to provide fair competition. This is referred to as "vehicle classing".
Currently, there are two primary sources of vehicle classing, based on the systems used by the two largest sanctioning bodies, the Sports Car Club of America (SCCA) and the National Auto Sport Association (NASA). Most of the smaller clubs and regional racing groups have adopted one of these two classing methods.

Autocross is extremely competitive. Active participants typically perform extensive modifications on their vehicles to get any advantage they can. Many vehicles are modified beyond the limit allowed for street legal use. Even "stock" class cars are seen being trailered to and from events, due to extreme wheel alignment adjustments. Competitors devote the majority of their efforts to suspension modifications to improve handling.
Because autocross involves operating the vehicle for a very short time, and involves extreme cornering and peak acceleration, many of the desired modifications seem counter-intuitive, and involve changing to smaller and lighter weight components, to reduce weight and improve power-to-weigh ratio. Many of these changes may not be suitable for use on the road or on a road course track.
Between the "stock" class trailered cars, and the non-street-legal, purpose built race cars, there are ample classes offering the opportunity for any car enthusiast to have a lot of fun with a street-able modified automobile.

SCCA - The Sports Car Club of America

The Sports Car Club of America (SCCA) brand of autocross is known as "Solo2". The SCCA has adopted a rigid structure which divides cars into groups from "unmodified" to highly modified (unlimited modifications), proscribing the specific modifications allowed in each class. Most of these classes are then subdivided with an alphabetic letter designation, grouping together specific models of vehicles which are of comparable performance level or description (engine displacement, body type, number of doors, etc.).
The caveat of the rules is "If the rule book specifically says you can do it, then its allowed, if the rule book doesn't specifically say you can do it, then you can't do it.". Building a "competitive" car involves determining the vehicle's class, reading the rules, and performing or installing every single modification allowed within the class rules. Although, the SCCA states that they "Do not guarantee every car will be competitive.".
In addition to the classing system, the SCCA has created an index system called "PAX", based on historic class results, which assigns an index coefficient to each class subdivision, with the goal of removing the vehicle's performance from the results, and allowing for comparison of the drivers' abilities across the various classes of competition. This, however, assumes that everyone is driving the most competitive car, that every car is prepared to the limit of the class rules, and every car is adjusted to its optimum performance.

The SCCA has reasonably thorough nationwide coverage and it is possible to find an autocross event within 300 miles of just about everywhere at least once a month during the summer months.

Criticisms of the SCCA's program include:
• New competitors show up to their first event and discover that they have made a modification to their vehicle which does not yield much performance advantage, but puts them into a class where their car and the rest of its preparation are completely uncompetitive.
• Allowable modifications for the various classes has never kept up with the current technology of automotive tuning and the modifications that normal people typically perform to modern vehicles. The SCCA's rule set has often been characterized as being based on "push rod and carburetor technology".
• The rules allow for up-dating and back-dating of cars listed on the same line in the Appendix lists. Laziness by the national officials groups dis-similar cars with the same model name, but which do not chare the same chassis components or engines, instead of a thorough distribution of the various trim levels within a model range into their appropriate class. This discourages development of anything but the top trim level of a model, and encourages the creation of "Franken-Cars", cherry picking the lightest body parts and largest engines from dissimilar chassis parts and engines in combinations which were never offered by the vehicle manufacturers. This is highly advantageous for vehicle models available across 20-30 year ranges, and highly disadvantageous to vehicle models available over a short time period or which were essentially unchanged over their availability.
• Engine modifications are not allowed in a logical ascending level across the range from "stock" to "unlimited" classes. Modification of anything between the valve cover and the oil pan is prohibited across the lower 3/4 of the classing structure, and then the rules make a sudden jump to allow engine swaps and unrestricted engine modifications. With a single step, allowed engine modifications go from exterior bolt-ons, to completely unrestricted, built-to-the-hilt, full-race, unlimited horsepower, fire breathing monsters. This is not consistent with the logical and gradual scale of allowable suspension modifications across the same range of classes.
• Car classing and re-classing decisions are based on the number of requests/complaints, and the quantity of member feedback, instead of empirical evidence. Other club organizations, such as the BMW Car Club of America, and groups of owners of popular cars, such as Mazda Miata, exert undue influence over classing and reclassification decisions. As a result, many specific sub-classes appear to be set-aside guaranteed national championship wins for competitors driving over-dog cars grouped with cars that are conspicuously and historically slower, poorer handling, less powerful, and mechanically competitively disadvantaged.
• Rule interpretation by national and local race officials often ignores what is actually written down in the rule book, and is primarily dependent upon the desired outcome of the official or the protected owners' group. (See above re: set-aside cub classes).
• Success beyond the Regional level, and "National Competitiveness", is dependent upon a skilled driver selecting, purchasing, and building a car that is favorably classed (See above re: set-aside cub classes). Because those favorably classed cars have an advantage that guarantees them a win. Some have suggested that the organization name should be changed to the "Sports Driver Club of America", because your favorite make or model of car is most likely is not among the chosen few, favorably classed, over-dogs.
• Rule changes, either re-classing cars up or down to enhance competition, or simply updating to meet the current technology, is painfully slow. The justification being that the organization does not want to alienate or negatively impact long time racers who have money invested in building class dominating car models and individual modifications to those cars.




The SCCA Classes for Geo Storm

• Stock - H Stock
  Stock class was defined as follows: Stock Category cars must be run as specified by the factory with only standard equipment (as defined by these Rules).
  Stock class was originally intended to be made up of completely unmodified vehicles as they rolled off of the showroom floor. Allowances were made for replacement of "wear" parts, and replacement of tires, shocks, and cat-back exhaust with aftermarket replacement parts, and no limitation upon the performance enhancement provided by these items. Very quickly, "Stock" class cars were no longer "stock".
  Stock class was phased out as of 2014. The class increasingly allowed replacement of "wear" parts with replacement parts that provide increased performance, and there had been a decline in class participation. This may have been because racers desire more modifications, but the SCCA believed this is a resistance to the cost of Stock class allowed R-Compound racing tires. The SCCA phased Stock out, and replaced it with "Street" class, with a few additional allowed modifications, and requirement for treaded tires with a higher tread wear rating, which they believe to be less expensive.
• Street - H Street (HS)
  Established in 2014 and replaced Stock classes in 2015. Adopts former Stock class rules with a few additional performance modifications, but does not allow R Compound racing tires, and limits tires to treaded tires commonly described as "extreme performance summer tires" with a 200 tread wear rating.
• Super Street-R (SSR)
  In 2014, this was used as a transition class allowing Stock cars with R Compound tires to continue for the 2014 season.
  In 2015, this class was reduced from A thorugh H to a single class intended for high horsepower cars with the limited Street category modifications to take advantage of the additional needed grip of R Compound tires.
  There is no direct statement in the current rules, but through 2014, the SCCA had stated that vehicles prepared to the former Stock and current Street rule set would be permitted to continue competing on R Compound tires in the SSR class, though all grouped together in a class designed specifically for Chevrolet Corvette, Dodge Viper, and Porsche 911.
• Street Touring Sport (STS)
  Beginning in 2015, the Street Touring Compact (STC) category has been merged with the Street Touring Sport (STS) class, and STS is no longer a nationally recognized category.
  Street Touring category is described as: A natural competition outlet for auto enthusiasts using affordable sports cars and sedans equipped with common suspension and engine modifications compatible with street use.
  Street Touring Compact is additionally described to include: Sedans & Coupes NOC (non-sports-car-based; 4-seat minimum; up to 3.1L normally-aspirated).
  The Street Touring classes were created to provide a place for modern mildly modified cars following the sport compact trend. These cars, with primarily cosmetic aero enhancements, would have previously been classed with highly modified cars, due to one or two modifications which do not significantly improve performance on an autocross course. The Street Touring classes have since been fine tuned so that they are positioned between the Stock/Street and Street Prepared classes.
• Street Touring X - Specific to the Impulse RS AWD Turbo sister car
  Street Touring category is described as: A natural competition outlet for auto enthusiasts using affordable sports cars and sedans equipped with common suspension and engine modifications compatible with street use.
  Street Touring X is additionally described to include: Sedans & Coupes NOC (non-sports-car-based; 4-seat minimum; 3.1L to 5.1L normally aspirated or up to 2.0L forced induction).
  The Street Touring classes were created to provide a place for modern mildly modified cars following the sport compact trend. These cars, with primarily cosmetic aero enhancements, would have previously been classed with highly modified cars, due to one or two modifications which do not significantly improve performance on an autocross course. The Street Touring classes have since been fine tuned so that they are positioned between the Stock/Street and Street Prepared classes.
• Street Prepared - F Street Prepared
  Street Prepared is described as allowing for mild modifications for street legal vehicles.
  Street Prepared classes allow for significant suspension modifications, but confine engine modifications to bolt on parts. The fuel injection and ignition systems are largely unlimited, allowing for programmable engine control systems. But everything within the engine itself, between the valve cover and the oil pan, must remain stock.
  Storm GSi and Base model are both placed in F Street Prepared, while the DOHC equipped Isuzu Impulse and Stylus are placed in the quicker D Street Prepared class. This represents an advantage for the Storm, because the Street Prepared rules allow modification of all of the parts that are different between the Storm GSi and the Impulse XS and Stylus XS and RS (the Lotus Tuned Suspension parts and the rear disc brakes). So simply changing the Storm GSi suspension and brakes over to those of the Impulse XS/Stylus XS/RS, results in a car that would be in DSP if it had an Isuzu badge, but it is allowed to run in FSP simply because it has a Geo badge. In addition to this, the Storm GSi further benefits from a quicker ratio steering rack, which is both advantageous, and prohibited from modification in Street Prepared, making the car quicker than the Impulse and Stylus that are forced to run in DSP.
• Street Modified (SM)
  Street Modified category is described as: A natural competition outlet for auto enthusiasts using streetable sport sedans equipped with drivetrain and suspension modifications that are beyond those allowed in the Street Prepared category.
  Regular Street Modified is additionally described as including: All sedans/coupes (models which were originally equipped with a minimum of four seats and four factory seat belts, not sports car based).
  Street Modified F is additionally described to include: All front-wheel-drive vehicles.
  The Street Modified classes are a break off from the Street Touring classes, roughly approximating allowances for highly modified sport compact type vehicles, and modern vehicles following the modifying trends popularized by the sport compact car trend. These are the lowest level of classes allowing for turbocharging and supercharging of cars which were not originally turbocharged or supercharged. The Street Modified classes have evolved to a position between the Street Prepared and Prepared classes.
• Street Modified Front Wheel Drive (SMF)
  Street Modified category is described as: A natural competition outlet for auto enthusiasts using streetable sport sedans equipped with drivetrain and suspension modifications that are beyond those allowed in the Street Prepared category.
  Street Modified F is additionally described to include: All front-wheel-drive vehicles.
  The Street Modified classes are a break off from the Street Touring classes, roughly approximating allowances for highly modified sport compact type vehicles, and modern vehicles following the modifying trends popularized by the sport compact car trend. These are the lowest level of classes allowing for turbocharging and supercharging of cars which were not originally turbocharged or supercharged. The Street Modified classes have evolved to a position between the Street Prepared and Prepared classes.
• Prepared - E Prepared
  (Impulse RS AWD - C Prepared or F Prepared)
  Prepared category is described as: Allowing modifications useful and necessary in the preparation of a high performance, production based non-street-driven vehicle.
  Prepared class follows the traditional progression from Stock, through Street Prepared, allowing significant suspension modifications, and adding allowances for significant internal engine modifications.
• X Prepared (XP)
  X Prepared allows for additional modifications above the rest of the Prepared classes, and provides a class for non-US spec vehicles and kit cars.
  X Prepared is an evolution from the foerm A Prepared class. The new intent is to provide allowances above and beyond the regular Prepared classes, and also to provide for non-US spec cars (usually imported JDM spec or European spec cars, often with right hand drive), and several approved kit cars. X Prepared also allows for some rather wild engine swaps.
• Modified - D Modified
  Modified category is defined as: Sports cars and sedans altered in excess of Prepared Category.
  D Modified is additionally described as: Modified Production and GT cars with internal combustion engine displacement 2000cc and under.
  Modified classes allow just about any modification to suspension or engine.


Cheating and Protests
After the competitors have made their runs, the cars are left in the grid with the hoods open in "impound". This provides the drivers the opportunity to examine the other competitor's cars and, in the event that they spot something that they believe is illegal, file a protest.
The protestor must be specific to the item and nature of the violation, meaning that a protest for one thing that reveals another violation may not be amended to include the additional violation.
The driver being protested is considered "guilty until proven innocent". The protestee must provide any and all documentation to prove that the item being protested is not in violation of the rules. This will include any and all shop manuals and parts catalogs from the vehicle manufacturer, as well as scale drawings and specifications of any reproduction aftermarket parts.
In the event that the item being protested is inside the engine, the protestor may be required to provide a disassembly bond (somewhere between $50 and $300). In the event that the protest is upheld, the bond is returned to the protestor. In the event that the bond is denied and no violation is found, the bond is turned over to the protestee to cover the cost of reassembly. However, even the maximum of $300 is hardly enough to cover the cost of gaskets and an engine rebuild, along with the cost of towing the car home with the engine disassembled and loaded into the trunk.

It is tempting to listen to people who say "Oh, no one will bother if you do this or that.". But there are few things that participants take more seriously than auto racing. If someone shows up to an event with something that is obviously illegal for the class they are running in, and wins, they can count on being protested. If a competitor sees something that is illegal, they will likely mention it with a suggestion to correct the car's class entry.
It is also tempting to listen to people who say "No one knows what these cars look like, they won't be able to tell what is original or not.". This, however, ignores the fact that the burden of proof is on the protestee, who must provide shop manuals, parts catalogs, and any documentation needed to prove that the item being protested is not illegal.
Rest assured, if someone shows up with a set of lime green racing seats in Stock/Street class, or a giant rear wing in Street Touring or Street Prepared and their class entry will be corrected or their results disqualified.
And keep in mind that people who autocross seriously are slightly more knoledgable about cars, even Isuzu made cars, than the general population. They know what a 1990's Japanese car is supposed to look like and what performance parts for a 1990's Japanese car look like. Spotting non-standard engine and suspension parts will not be very difficult.
It just isn't worth turning generally friendly group of racers, in the local region, into enemies. And winning means a little more with the confidence that the winning car is 100% legal and complies with the rules.


The following chart is based on interpretation of the current SCCA rulebook. Interpretation is subject to debate. Check the rule book yourself before making any decisions and consult with the SEB in the event of any questions.
The complete rule book is available online as a PDF file on the SCCA website.

The following chart has been tailored specifically to the classes and modifications which are common to and logical for the Geo Storm and its Isuzu sister cars.
Impulse RS AWD has been included because it is often of particular interest to Storm owners.
The modification categories have been laid out in a similar pattern as the SCCA rule book. This pattern reveals the concerns and priorities of the SCCA in regulating competition. Some format order changes have been made to present related topics together.

Bodywork Modifications; Interior

Modification	Street (Replaced Stock in 2015)	Super Street-R	Street Touring Sport (STS)	Street Touring X (STX) (Impulse RS AWD)	Street Prepared	Street Modified (SM)	Street Modified FWD (SMF)	Prepared	X Prepared	Modified
Accessories, gauges, indicators, lights and other appearance, comfort and convenience modifications	Yes	Yes	Yes	Yes	Yes	Yes	Yes	Yes	Yes	Yes
Disable Airbag Electrically	Yes	Yes	Yes	Yes	Yes	Yes	Yes	Yes	Yes	Yes
Physically Remove Airbag Mechanism	No	No	No	No	Yes	Yes	Yes	Yes	Yes	Yes
Change Steering Wheel	No, Airbag	No, Airbag	No, Airbag	No, Airbag	Yes	Yes	Yes	Yes	Yes	Yes
Racing Harness	Yes	Yes	Yes	Yes	Yes	Yes	Yes	Yes	Yes	Yes
Short Throw Shift Kit	No	No	Yes	Yes	Yes	Yes	Yes	Yes	Yes	Yes
Pedal Covers	No	No	Yes	Yes	Yes	Yes	Yes	Yes	Yes	Yes
Change Driver Seat	No	No	Yes	Yes	Yes	Yes	Yes	Yes	Yes	Yes
Change Passenger Seat	No	No	Yes	Yes	Yes	Yes	Yes	Yes	Yes	Yes
Driver & Passenger Seat Minimum Weight	NA	NA	25 lb.	25 lb.	NA	NA	NA	NA	NA	NA
Remove Spare Tire, Jack, Etc.	Yes	Yes	Yes	Yes	Yes	Yes	Yes	Yes	Yes	Yes
Radio Delete	No	No	No	No	Yes	Yes	Yes	Yes	Yes	Yes
Air Conditioner Delete	No	No	No	No	Yes	Yes	Yes	Yes	Yes	Yes
Remove Rear Seats	No	No	No	No	No	Yes	Yes	Yes	Yes	Yes
Remove Passenger Seat	No	No	No	No	No	No	No	Yes	Yes	Yes
Strip Interior	No	No	No	No	No	No	No	Yes	Yes	Yes
Roll Bar/Hoop	Yes	Yes	Yes	Yes	Yes	Yes	Yes	Yes	Yes	Yes
Bolt-In Roll Cage	Yes	Yes	Yes	Yes	Yes	Yes	Yes	Yes	Yes	Yes
Welded Roll Cage	No	No	No	No	Yes	Yes	Yes	Yes	Yes	Yes



Bodywork Modifications; Chassis

Modification	Street (Replaced Stock in 2015)	Super Street-R	Street Touring Sport (STS)	Street Touring X (STX) (Impulse RS AWD)	Street Prepared	Street Modified (SM)	Street Modified FWD (SMF)	Prepared	X Prepared	Modified
Two Point Strut Braces (Front and Rear) (Non-Triangulated)	No	No	Yes	Yes	Yes	Yes	Yes	Yes	Yes	Yes
Two Point Lower Tie Bars (Front and Rear) (Non-Triangulated)	No	No	Yes	Yes	Yes	Yes	Yes	Yes	Yes	Yes
Longitudinal Subframe Connectors	No	No	Yes	Yes	Yes	Yes	Yes	Yes	Yes	Yes
Reinforce Chassis	No	No	No	No	No	No	No	Yes	Yes	Yes
Disable Rear Wheel Steering Mechanism	No	No	No	No	No	Yes	Yes	Yes	Yes	Yes



Bodywork Modifications; Exterior

Modification	Street (Replaced Stock in 2015)	Super Street-R	Street Touring Sport (STS)	Street Touring X (STX) (Impulse RS AWD)	Street Prepared	Street Modified (SM)	Street Modified FWD (SMF)	Prepared	X Prepared	Modified
Remove Emblems, Garnish, Foglights	No	No	Yes	Yes	Yes	Yes	Yes	Yes	Yes	Yes
Roll Fender Lips	No	No	Yes	Yes	Yes	Yes	Yes	Yes	Yes	Yes
Cut Fenders (For Tire Clearance)	No	No	No	No	No	Yes	Yes	Yes	Yes	Yes
Sunroof Delete Via Replacing Steel Roof	No	No	No	No	Yes	Yes	Yes	Yes	Yes	Yes
Alternate Sunroof Panel	No	No	No	No	No	Yes	Yes	Yes	Yes	Yes
Polycarbonate Windows	No	No	No	No	No	No	No	Yes	Yes	Yes
Add OEM Aero, Spoiler, Wing, and Trim Parts	No	No	Yes	Yes	Yes	Yes	Yes	Yes	Yes	Yes
Front Spoiler, Air Dam Below Bumper, or Small Splitter (May Not Protrude Beyond Edge Of Bumper)	No	No	No	No	Yes	Yes	Yes	Yes	Yes	Yes
Front Splitter Extending 6 Inches In Front Of Bumper	No	No	No	No	No	Yes	Yes	No	Yes	No
Rear Spoiler (Non-Wing, 10 Inch Tall Limit)	No	No	No	No	Yes	Yes	Yes	Yes	Yes	Yes
Rear Wing (8 Square Foot Area Limit)	No	No	No	No	No	Yes	Yes	No	Yes	No
Canards (1.2 Square Foot Area Limit)	No	No	No	No	No	Yes	Yes	No	Yes	No
Fiberglass or Carbon Fiber Hoods, Fenders, Front and Rear Fascias	No	No	No	No	No	Yes	Yes	Yes	Yes	Yes
Hood Vents and Louvers	No	No	No	No	No	No	No	Yes	Yes	Yes
Fiberglass or Carbon Fiber Hatch	No	No	No	No	No	No	No	Yes	Yes	Yes
Fiberglass or Carbon Fiber Doors	No	No	No	No	No	No	No	No	No	Yes
Remove Bumpers	No	No	No	No	No	No	No	Yes	Yes	Yes
Remove Exterior Lights and Lamps	No	No	No	No	No	No	No	Yes	Yes	Yes
Notched Rear Bumper	No	No	No	No	No	No	No	Yes	Yes	Yes
Rear Diffuser	No	No	No	No	No	No	No	No	No	Yes
Shape of Bumpers, Fenders, Hoods, Hatches, Fascias and Any Bolt On Panel May Be Freely Altered (Includes Wide Body Fenders)	No	No	No	No	No	No	No	No	Yes	Yes



Tire Modifications

Modification	Street (Replaced Stock in 2015)	Super Street-R	Street Touring Sport (STS)	Street Touring X (STX) (Impulse RS AWD)	Street Prepared	Street Modified (SM)	Street Modified FWD (SMF)	Prepared	X Prepared	Modified
Minimum Tread Wear Rating	200	NA	200	200	NA	NA	NA	NA	NA	NA
Minimum Molded Tread Depth	7/32"	NA	7/32"	7/32"	NA	NA	NA	NA	NA	NA
R-Compound Tire	No	Yes	No	No	Yes	Yes	Yes	Yes	Yes	Yes
Maximum Tread Width	Stock	Stock	225	245	Any	Any	Any	Any	Any	Any



Wheel Modifications

Modification	Street (Replaced Stock in 2015)	Super Street-R	Street Touring Sport (STS)	Street Touring X (STX) (Impulse RS AWD)	Street Prepared	Street Modified (SM)	Street Modified FWD (SMF)	Prepared	X Prepared	Modified
Change Wheel Size	Yes	No	Yes	Yes	Yes	Yes	Yes	Yes	Yes	Yes
Change Wheel Offset	+/- 1/4"	+/- 1/4"	Yes	Yes	Yes	Yes	Yes	Yes	Yes	Yes
Maximum Wheel Width	Stock	Stock	7.5"	8.0"	Any	Any	Any	7.0" More With Weight Penalty	Any	Any
Maximum Wheel Diameter	1 Inch Larger Than Stock	Stock	Any	Any	Any	Any	Any	Any	Any	Any
Wheel Spacers	No	No	Yes	Yes	Yes	Yes	Yes	Yes	Yes	Yes



Brake System Modifications

Modification	Street (Replaced Stock in 2015)	Super Street-R	Street Touring Sport (STS)	Street Touring X (STX) (Impulse RS AWD)	Street Prepared	Street Modified (SM)	Street Modified FWD (SMF)	Prepared	X Prepared	Modified
Upgrade Brake Pads and/or Shoes	Yes	Yes	Yes	Yes	Yes	Yes	Yes	Yes	Yes	Yes
Stainless Steel Brake Lines (20+ Year Old Cars) (DOT Approved)	Yes	Yes	Yes	Yes	Yes	Yes	Yes	Yes	Yes	Yes
Cross Drilled and/or Slotted Rotors	No	No	Yes	Yes	Yes	Yes	Yes	Yes	Yes	Yes
Change From Drum Brakes To Disc Brakes	No	No	Yes	Yes	Yes	Yes	Yes	Yes	Yes	Yes
Any Ferrous Brake Rotor, Equal To Or Larger Than OEM	No	No	Yes	Yes	Yes	Yes	Yes	Yes	Yes	Yes
Any Size Ferrous Brake Rotor (Smaller, Weight Reduction)	No	No	No	No	No	Yes	Yes	Yes	Yes	Yes
Any Size Brake Rotor, Any Material (Smaller, Non-Ferrous, Weight Reduction)	No	No	No	No	No	No	No	Yes	Yes	Yes
Any Brake Caliper (Multi-Piston)	No	No	Yes	Yes	Yes	Yes	Yes	Yes	Yes	Yes
Big Brake Kit	No	No	Yes	Yes	Yes	Yes	Yes	Yes	Yes	Yes
Add Brake Cooling Ducts	No	No	No	No	Yes	Yes	Yes	Yes	Yes	Yes
Delete Emergency / Parking Brake, Or In Any Way Render Non-Functional	No	No	No	No	No	No	No	Yes	Yes	Yes
Disable ABS	No	No	Yes	Yes	Yes	Yes	Yes	Yes	Yes	Yes
Remove ABS Mechanism	No	No	No	No	No	Yes	Yes	Yes	Yes	Yes
Add Brake Proportioning Valve	No	No	No	No	Yes	Yes	Yes	Yes	Yes	Yes
Inboard Brakes	No	No	No	No	No	No	No	No	No	Yes



Anti Roll (Sway) Bar Modifications

Modification	Street (Replaced Stock in 2015)	Super Street-R	Street Touring Sport (STS)	Street Touring X (STX) (Impulse RS AWD)	Street Prepared	Street Modified (SM)	Street Modified FWD (SMF)	Prepared	X Prepared	Modified
Add, Remove, or Modify One Sway Bar (Front or Rear)	Yes	Yes	Yes	Yes	Yes	Yes	Yes	Yes	Yes	Yes
Add, Remove, or Modify Both Sway Bars	No	No	Yes	Yes	Yes	Yes	Yes	Yes	Yes	Yes
Change Sway Bar Bushing Material (Polyurethane)	Yes	Yes	Yes	Yes	Yes	Yes	Yes	Yes	Yes	Yes



Shock Absorber Modifications

Modification	Street (Replaced Stock in 2015)	Super Street-R	Street Touring Sport (STS)	Street Touring X (STX) (Impulse RS AWD)	Street Prepared	Street Modified (SM)	Street Modified FWD (SMF)	Prepared	X Prepared	Modified
Any Two Way Adjustable Damper	Yes	Yes	Yes	Yes	Yes	Yes	Yes	Yes	Yes	Yes
Change Strut Housing Dimensions	No	No	Yes	Yes	Yes	Yes	Yes	Yes	Yes	Yes
Adjustable Spring Perch	No	No	Yes	Yes	Yes	Yes	Yes	Yes	Yes	Yes
Coilovers	No	No	Yes	Yes	Yes	Yes	Yes	Yes	Yes	Yes



Suspension Modifications

Modification	Street (Replaced Stock in 2015)	Super Street-R	Street Touring Sport (STS)	Street Touring X (STX) (Impulse RS AWD)	Street Prepared	Street Modified (SM)	Street Modified FWD (SMF)	Prepared	X Prepared	Modified
Crash Bolts / Camber Bolts	No-Not OEM	No-Not OEM	Yes	Yes	Yes	Yes	Yes	Yes	Yes	Yes
Slot Suspension Mount Holes	No-Not OEM	No-Not OEM	Yes	Yes	Yes	Yes	Yes	Yes	Yes	Yes
Camber Plates	No	No	Yes	Yes	Yes	Yes	Yes	Yes	Yes	Yes
Change to Another Power Steering Rack (Change Ratio)	No	No	Yes	Yes	No	Yes	Yes	Yes	Yes	Yes
Change Steering Rack Bushings (Polyurethane)	No	No	No	No	Yes	Yes	Yes	Yes	Yes	Yes
Delete Power Steering	No	No	No	No	No	Yes	Yes	Yes	Yes	Yes
Change Ride Height	No	No	Yes	Yes	Yes	Yes	Yes	Yes	Yes	Yes
Change Spring Rate	No	No	Yes	Yes	Yes	Yes	Yes	Yes	Yes	Yes
Use Any (Non-OEM) Coil Spring	No	No	Yes	Yes	Yes	Yes	Yes	Yes	Yes	Yes
Change Suspension Bushing Material (Polyurethane)	No	No	Yes	Yes	Yes	Yes	Yes	Yes	Yes	Yes
Change Differential Carrier Bushing Material (Polyurethane)	No	No	Yes	Yes	Yes	Yes	NA	Yes	Yes	Yes
Change Subframe Bushing Material (Polyurethane)	No	No	Yes	Yes	Yes	Yes	NA	Yes	Yes	Yes
Heim Joint Suspension Joints	No	No	No	No	No	Yes	Yes	Yes	Yes	Yes
Modify/Reinforce Suspension Arms	No	No	No	No	Yes	Yes	Yes	Yes	Yes	Yes
Roll Center Correction / Extended Ball Joints	No	No	No	No	No	Yes	Yes	Yes	Yes	Yes
Convert Front Suspension to Double Wishbone / A Arm	No	No	No	No	No	No	No	Yes	Yes	Yes
Change/Relocate Suspension Mounting Points	No	No	No	No	No	No	No	Yes	Yes	Yes
Convert Rear Suspension to Double Wishbone / A Arm	No	No	No	No	No	No	No	No	Yes	Yes



Electrical And Ignition System Modifications

Modification	Street (Replaced Stock in 2015)	Super Street-R	Street Touring Sport (STS)	Street Touring X (STX) (Impulse RS AWD)	Street Prepared	Street Modified (SM)	Street Modified FWD (SMF)	Prepared	X Prepared	Modified
Smaller (Racing) Battery	No	No	Yes	Yes	Yes	Yes	Yes	Yes	Yes	Yes
Battery Relocation	No	No	Yes	Yes	Yes	Yes	Yes	Yes	Yes	Yes
Larger Alternator	No	No	No	No	Yes	Yes	Yes	Yes	Yes	Yes
Smaller Alternator	No	No	No	No	No	Yes	Yes	Yes	Yes	Yes
Any OEM Replacement Spark Plug	Yes	Yes	Yes	Yes	Yes	Yes	Yes	Yes	Yes	Yes
Any OEM Replacement Ignition Wires	Yes	Yes	Yes	Yes	Yes	Yes	Yes	Yes	Yes	Yes
Ignition System, Multi-Strike, Etc.	No	No	No	No	Yes	Yes	Yes	Yes	Yes	Yes
Coil On Plug Conversion (Multiple Ignition Coils)	No	No	No	No	Yes	Yes	Yes	Yes	Yes	Yes



Engine Modifications - Intake and Exhaust

Modification	Street (Replaced Stock in 2015)	Super Street-R	Street Touring Sport (STS)	Street Touring X (STX) (Impulse RS AWD)	Street Prepared	Street Modified (SM)	Street Modified FWD (SMF)	Prepared	X Prepared	Modified
Drop In Air Filter	Yes	Yes	Yes	Yes	Yes	Yes	Yes	Yes	Yes	Yes
Cold Air Intake With Cone Filter	No	No	Yes	Yes	Yes	Yes	Yes	Yes	Yes	Yes
Larger Throttlebody	No	No	No	No	Yes	Yes	Yes	Yes	Yes	Yes
Modified, Different Intake Manifold	No	No	No	No	Yes	Yes	Yes	Yes	Yes	Yes
Cat Back Exhaust	Yes	Yes	Yes	Yes	Yes	Yes	Yes	Yes	Yes	Yes
Exhaust Header	No	No	Yes	Yes	Yes	Yes	Yes	Yes	Yes	Yes
Upgrade Down Pipe (Impulse RS AWD)	No	No	NA	Yes	Yes	Yes	NA	Yes	Yes	Yes
High Flow Catalytic Converter	No	No	Yes	Yes	Yes	Yes	Yes	Yes	Yes	Yes
Remove and/or Disable Emissions Control Devices	No	No	No	No	Yes	Yes	Yes	Yes	Yes	Yes



Engine Modifications - Fuel Delivery

Modification	Street (Replaced Stock in 2015)	Super Street-R	Street Touring Sport (STS)	Street Touring X (STX) (Impulse RS AWD)	Street Prepared	Street Modified (SM)	Street Modified FWD (SMF)	Prepared	X Prepared	Modified
Convert To Carburetor	No	No	No	No	Yes	Yes	Yes	Yes	Yes	Yes
Convert To Multi/Individual Throttle Body Fuel Injection	No	No	No	No	Yes	Yes	Yes	Yes	Yes	Yes
Reprogram OEM ECU or Piggyback Controller	No	No	Yes	Yes	Yes	Yes	Yes	Yes	Yes	Yes
Stand Alone Engine Control System	No	No	No	No	Yes	Yes	Yes	Yes	Yes	Yes
Convert From Batch Fire To Sequential Fuel Injection	No	No	No	No	Yes	Yes	Yes	Yes	Yes	Yes
Change Fuel Injector Size	No	No	No	No	Yes	Yes	Yes	Yes	Yes	Yes
Change Fuel Pressure Regulator	No	No	No	No	Unclear	Yes	Yes	Yes	Yes	Yes
Change Fuel Pump Size	No	No	No	No	Yes	Yes	Yes	Yes	Yes	Yes
Change Fuel Cell	No	No	No	No	+/-20% of OEM	5 Gal. Min.	Yes	Yes	Yes	Yes
Add Intake Water Injection System	No	No	No	No	Yes	Yes	Yes	Yes	Yes	Yes



Engine Modifications - Engine Building

Modification	Street (Replaced Stock in 2015)	Super Street-R	Street Touring Sport (STS)	Street Touring X (STX) (Impulse RS AWD)	Street Prepared	Street Modified (SM)	Street Modified FWD (SMF)	Prepared	X Prepared	Modified
Stock Spec Minimum Overbore Engine Rebuild	.020" Limit	.020" Limit	Yes	Yes	.0472" Limit	Yes	Yes	Yes	Yes	Yes
Balance, But Not Lighten, Rotating and Reciprocating Parts	No	No	No	No	Yes	Yes	Yes	Yes	Yes	Yes
Adjustable Cam Sprockets	No	No	No	No	Yes	Yes	Yes	Yes	Yes	Yes
Port Match Head One Inch Depth	No	No	No	No	Yes	Yes	Yes	Yes	Yes	Yes
Racing Engine Rebuild, Unrestricted: Pistons, Rods, Crankshaft, Camshafts, Etc.	No	No	No	No	No	Yes	Yes	Yes	Yes	Yes
Change Pistons (Reduce Weight, Raise/Lower Compression)	No	No	No	No	No	Yes	Yes	Yes	Yes	Yes
Change Connecting Rods (Light Weight, Change Length)	No	No	No	No	No	Yes	Yes	Yes	Yes	Yes
Change Crankshaft (Lighten, Change Stroke)	No	No	No	No	No	Yes	Yes	Yes	Yes	Yes
Change Camshaft Camshafts (Lift, Duration)	No	No	No	No	No	Yes	Yes	Yes	Yes	Yes
Change Valves (Stainless, Titanium, Larger, Etc.)	No	No	No	No	No	Yes	Yes	Yes	Yes	Yes
Change Valve Springs (Single, Double, Etc.)	No	No	No	No	No	Yes	Yes	Yes	Yes	Yes
Change Valve Spring Retainers (Stainless, Titanium, Shim Under, Etc.)	No	No	No	No	No	Yes	Yes	Yes	Yes	Yes
Change Lifter / Cam Follower Type (Solid, Hydraulic)	No	No	No	No	No	Yes	Yes	Yes	Yes	Yes
Change To Shim Under Bucket Lifters	No	No	No	No	No	Yes	Yes	Yes	Yes	Yes
Unrestricted Head Porting	No	No	No	No	No	Yes	Yes	Yes	Yes	Yes
Change Oil Pan	No	No	Yes	Yes	Yes	Yes	Yes	Yes	Yes	Yes
Add Windage Tray (If Not OEM)	No	No	Yes	Yes	No	Yes	Yes	Yes	Yes	Yes
Add Crank Scraper	No	No	No	No	No	No	No	Yes	Yes	Yes
Engine Swap Block From Same Vehicle Manufacturer	No	No	No	No	No	Yes	Yes	Yes	Yes	Yes
Engine Swap, Any Automobile Engine	No	No	No	No	No	No	No	No	Yes	Yes
Aluminum Underdrive Crank Pulley and Accessory Pulleys	No	No	Yes	Yes	Yes	Yes	Yes	Yes	Yes	Yes



Engine Modifications - Cooling System

Modification	Street (Replaced Stock in 2015)	Super Street-R	Street Touring Sport (STS)	Street Touring X (STX) (Impulse RS AWD)	Street Prepared	Street Modified (SM)	Street Modified FWD (SMF)	Prepared	X Prepared	Modified
Any OEM Fit Radiator Of Equal Or Greater Core Thickness	No	No	No	No	Yes	Yes	Yes	Yes	Yes	Yes
Smaller Radiator (Weight Reduction)	No	No	No	No	No	No	No	Yes	Yes	Yes
Change Cooling Fan and/or Fan Shroud	No	No	No	No	Yes	Yes	Yes	Yes	Yes	Yes
Add Oil Cooler	No	No	No	No	Yes	Yes	Yes	Yes	Yes	Yes
Add Electric Fan To Oil Cooler	No	No	No	No	No	No	No	Yes	Yes	Yes



Engine Modifications - Forced Induction System

Modification	Street (Replaced Stock in 2015)	Super Street-R	Street Touring Sport (STS)	Street Touring X (STX) (Impulse RS AWD)	Street Prepared	Street Modified (SM)	Street Modified FWD (SMF)	Prepared	X Prepared	Modified
Change Turbo Manifold of OEM Turbo (Impulse RS AWD)	No	No	No	No	Yes	Yes	NA	Yes	Yes	Yes
Add or Upgrade Blow Off Valve to OEM Turbo (Impulse RS AWD)	No	No	No	No	Yes	Yes	NA	Yes	Yes	Yes
Change Intercooler of OEM Turbo (Impulse RS AWD)	No	No	No	No	Yes	Yes	NA	Yes	Yes	Yes
Boost Controller (Electronic or Manual) for OEM Turbo (Impulse RS AWD)	No	No	No	No	Yes	Yes	NA	Yes	Yes	Yes
Port Wastegate for OEM Turbo (Impulse RS AWD)	No	No	No	No	No	Yes	NA	Yes	Yes	Yes
Change Turbocharger for OEM Turbo (Impulse RS AWD)	No	No	No	No	No	Yes	NA	Yes	Yes	Yes
Add Turbocharger To Naturally Aspirated Car (Turbo Kit)	No	No	No	No	No	Yes	Yes	Move to CP or FP	Yes	Move to E Mod
Turbocharger Inlet Air Restrictor	NA	NA	NA	NA	NA	None	None	CP 52mm FP 46mm	None	None
Add Supercharger To Naturally Aspirated Car (Blower Kit)	No	No	No	No	No	Yes	Yes	Move to CP or FP	Yes	Move to E Mod



Engine Modifications - Mounting

Modification	Street (Replaced Stock in 2015)	Super Street-R	Street Touring Sport (STS)	Street Touring X (STX) (Impulse RS AWD)	Street Prepared	Street Modified (SM)	Street Modified FWD (SMF)	Prepared	X Prepared	Modified
Polyurethane Engine and Transmission Mount Bushings	No	No	Yes	Yes	Yes	Yes	Yes	Yes	Yes	Yes
Solid Metal Engine and Transmission Mount Bushings	No	No	No	No	No	Yes	Yes	Yes	Yes	Yes



Drivetrain Modifications

Modification	Street (Replaced Stock in 2015)	Super Street-R	Street Touring Sport (STS)	Street Touring X (STX) (Impulse RS AWD)	Street Prepared	Street Modified (SM)	Street Modified FWD (SMF)	Prepared	X Prepared	Modified
Add Limited Slip Differential(s)	No	No	No	Yes or One if AWD	Yes	Yes	Yes	Yes	Yes	Yes
Any Metal Clutch Assembly	No	No	No	No	Yes	Yes	Yes	Yes	Yes	Yes
Any Metal Flywheel (Aluminum)	No	No	No	No	Yes	Yes	Yes	Yes	Yes	Yes
Any Metal Torque Converter	No	No	No	No	Yes	Yes	Yes	Yes	Yes	Yes
Any Transmission Oil Cooler	No	No	No	No	Yes	Yes	Yes	Yes	Yes	Yes
Polyurethane Engine and Transmission Mount Bushings	No	No	Yes	Yes	Yes	Yes	Yes	Yes	Yes	Yes
Solid Metal Engine and Transmission Mount Bushings	No	No	No	No	No	Yes	Yes	Yes	Yes	Yes
Add One Torque Suppression Device	No	No	No	No	Yes	Yes	Yes	Yes	Yes	Yes
Unrestricted Number Of Torque Suppression Devices	No	No	No	No	No	No	No	Yes	Yes	Yes
Change Differential Carrier Bushing Material (Polyurethane)	No	No	Yes	Yes	Yes	Yes	NA	Yes	Yes	Yes
Any Transmission Any Gear Ratios, Any Final Drive Ratio	No	No	No	No	No	No	No	Yes	Yes	Yes

NASA - The National Auto Sport Association

The National Auto Sport Association (NASA) was started by SCCA members who were dissatisfied with the rules and hierarchy of the SCCA. NASA takes a decidedly different approach to car classing and fluidity of adjusting cars and modifications up or down the scale to level the field of competition. They apply the same classing structure to both autocross as they do to touring car club/road racing.
NASA has a very large presence on the East Coast, and a large presence in Southern California. The organization expanded rapidly toward the middle of the country, and introduced their brand of autocross, called NASAcross or NASAX. Unfortunately, the rapid rise did not stick, and their autocross program seems to have contracted to two strong East Coast regions.

The NASA classing system uses a single ladder of classes, assigning each make and model of car to a base class, and moving the car up to the next class rung based on points assigned to the modifications done to the car. This drastically reduces the number of classes and allowed the competitor to choose whichever modifications they desire.
The baseline class of a car is determined by the vehicle's power to weight ratio, total weight, engine torque measurement across engine RPM range, body style, engine location, suspension layout, and equipment technology. Baseline class may be adjusted up or down by the organization if the vehicle is proven to be an under-dog or an over-dog in competition.
Modified vehicles are moved up in class from their base class based on the total of points counted for the modifications done to the vehicle. If a car accumulates 20 points (including base class points if applicable), it moves up to the next class. In order to further equalize competition, cars can be classed "between" ladder rungs, by assigning 7 points (noted by a single asterisk) or 14 points (noted by two asterisks) to their base line classing. Note below that the Storm GSi has a single asterisk, meaning that it starts out with 7 points and makes its first bump up in class after accumulating 13 additional points.

As the point system has evolved, points levied for weight reduction, tire width changes, engine displacement changes, and compression ratio changes, have introduced a surprising level of complication to the formerly streamlined classing system. Weight reduction now involves the use of a scale. Engine swaps and turbocharger kits now involve submitting dyno results to the NasaX National Director.

This classing system seems less hostile to first time event participants (car enthusiasts) who have modified their car. This is because the new participant does not find themselves bumped up into an unreasonably high class due to one modification that the SCCA classing structure permits only in a class reserved for full race vehicles.

Conversely, the NASA classing system is not friendly to cars built to the SCCA rule set. A car built for Street Prepared class can easily accumulate 30-40+ points and find itself at a disadvantage against cars built with modifications tailored to match the car and the NASA points system, instead of an arbitrary recipe check list.

There is one major criticism of the NASA classing system:
• In order to find the highest performance level of the car, the participant must test every possible combination of available modifications which add up to the point limit for a class. Unless the vehicle is common and being raced by a large number of other participants, there is no source of shared testing or even opinion. Without that shared group knowledge, the competitor is on their own. Because each model of car responds differently to any given modification, finding the most potent mix would cost a fortune. And if the vehicle is not well catered to by a large aftermarket, the competitor is relying on custom made parts which are even more expensive.


Base classing for the Geo Storm is:
• NXG - Geo Storm Base/SOHC, Weight: 2282 lb.
• NXF* (*Base class starts with 7 points toward first bump) - Geo Storm GSi, Weight: 2480 lb.

NASA does not currently have the Isuzu sister cars formally classed. This could be done by contacting NASA. The Non-turbo Isuzu sister cars would probably be classed similarly to their Geo Storm Base/SOHC and GSi counterparts, and the Impulse RS AWD likely classed slightly higher.

Check the rule book yourself before making any decisions and consult with NASA in the event of any questions.
The base classing chart and modification points list is available online as a PDF file on the NASA website.
The following table is based on the current rule book.

Tires

Modification	Points
DOT-approved R-compound tires: BFG R1S, Hoosier Wet DOT	+15
DOT-approved R-compound tires: BFG R1, Goodyear Eagle RS AC (autocross), Hankook Z214 (C90 & C91 compounds only), Hoosier A6	+13
DOT-approved R-compound tires and those with a UTQG tread wear rating of 40 or less not listed otherwise in these rules: Maxxis RC-1(examples: Goodyear Eagle RS, Hankook Z214 (C71, C70, C51, C50), Hoosier R6, Kumho V710, etc. (note: Grand Am Continental Tire Sports Car Challenge tires OK)	+10
OT-approved R-compound tires: Toyo Proxes RR, Hankook TD	+10
DOT-approved R-compound tires with a UTQG treadwear rating of 50 to 130 (ex. Kumho V700, Michelin Pilot Sport Cup, Nitto NT01, Pirelli PZero Corsa, Toyo R888, Toyo RA-1, Yokahama A048, etc)	+7
DOT-approved (non-R-compound) tires with a UTQG treadwear rating of 120-200 (examples: Toyo R1R, Dunlop Direzza Sport Z1 Star Spec, Bridgestone Potenza RE070, Kumho Ecsta XS, Yokohama Advan A046 & Neova AD08, Hankook R-S3)	+2
Non-DOT-approved racing slicks	+30



Allowed Base Tire Size

Class	Width
NXR	335 mm
NXU	315 mm
NXS	305 mm
NXA	295 mm
NXB	265 mm
NXC	255 mm
NXD	245 mm
NXE	235 mm
NXF	215 mm
NXG	195 mm
NXH	175 mm



Change Tire Width

Modification	Points
+120 mm	+34
+110 mm	+31
+100 mm	+28
+90 mm	+25
+80 mm	+22
+70 mm	+19
+60 mm	+16
+50 mm	+13
+40 mm	+10
+30 mm	+7
+20 mm	+4
+10 mm	+1
+/-0 mm	-0-
-10 mm	-1
-20 mm	-4
-30 mm	-7
-40 mm	-10
-50 mm	-13
-60 mm	-16
-70 mm	-19
-80 mm	-21
-90 mm	-24
-100 mm	-28
-110 mm	-30
-120 mm	-34



Weight Reduction

Modification	Points
-5 lb.	+1
-20 lb.	+2
-35 lb.	+3
-50 lb.	+4
-65 lb.	+5
-80 lb.	+6
-95 lb.	+7
-110 lb.	+8
-125 lb.	+9
-140 lb.	+10
-155 lb.	+11
-170 lb.	+12
-1805 lb.	+13
-200 lb.	+14
-215 lb.	+15
-230 lb.	+16
-245 lb.	+17
-260 lb.	+18
-275 lb.	+19
-290 lb.	+20
-305 lb.	+21
-320 lb.	+22
-335 lb.	+23
-350 lb.	+24
-365 lb.	+25
-380 lb.	+26
-395 lb.	+27
-410 lb.	+28
-425 lb.	+29
-440 lb.	+30
-455 lb.	+31
-470 lb.	+32
-485 lb.	+33
-500 lb.	+34
Plus one additional point for each additional 15 pounds of weight reduction.	+Etc.

Instead of assigning points to individual weight reduction items, NASA assigns points to the number of pounds that the vehicle weight is reduced below the base weight listed with the vehicle class. For the Geo Storm entries, this appears to be the factory listed curb weight, which is an advantage because the curb weight is lower than the actual weight of an operable vehicle.

Engine / Drivetrain

Modification	Points
Engine swap: All engine swaps must be evaluated for new base classification by the NASA-X National Director on an individual basis, unless a base class for the particular swap is listed above in 1.2 Base Classifications or in Appendix A. Please refer to section 1.5.	+???
Non-OEM turbo or supercharger, upgraded or modified turbo/supercharger, increased number of camshafts or non-OEM (non-stock) head(s)/hybrids: same as 1), refer to sec 1.5.	+???
Aftermarket computer system (any non-OEM “stand-alone” or “piggyback”) - Naturally Aspirated	+3
Aftermarket computer system (any non-OEM “stand-alone” or “piggyback”) - Turbocharger/Supercharger	+10
Drop in air filter in OEM aif filter canister/box	+0
Modification of the OEM air intake/box, air filter location, air piping to the turbo/supercharger/ intercooler/throttle body/carburetor, or hood/fascia/fender air inlet(s), outlets, or vents	+1
Non-OEM, deleted, or modified/ported throttle body	+2
Independent/individual/multiple throttlebodies	+4
Non-OEM or modified carburetor, fuel rail, fuel injectors, fuel pump(s), and/or fuel pressure regulator	+2
Non-OEM, modified/ported, or deleted intake manifold: 4 cyl.	+1
Water injection system (alcohol-water mixtures are not permitted)	+6
Nitrous oxide injection is not permitted.	Not Permitted
Replacement pulleys (other than for supercharger) or non-electrical fan removal	+1
Replacement pulley for OEM supercharger or replacement of any pulley that affects OEM supercharger speed	+4
Aftermarket boost controller or modification/alteration of OEM vacuum lines that serve to function as a boost controller	+4
Aftermarket or modified wastegate actuator, wastegate, or vacuum line(s) that serve to control the wastegate actuator function or increase peak boost	+3
Add aftermarket intercooler	+7
Non-OEM or modified intercooler (Intercooler sprayers are not permitted unless they came on the OEM base trim model of the vehicle)	+4
Increased displacement by: <1.5%	+0
Increased displacement by: 1.5% to <5.5%	+4
Increased displacement by: 5.5% to <7%	+6
Increased displacement by: 7% to <10%	+8
Increased displacement by: 10% to <15%	+10
Increased displacement by: 15% to <20%	+15
Increased displacement by: > 20%	+20
Modified or non-OEM camshaft(s), rocker arms, push rods, or cam timing gears (for one or more)	+6
Valve size change, modified, ported or polished OEM head (other than simple shaving of the head only)	+6
Any modifications that result in increased engine compression ratio (including shaving the head or decking the block to factory specs): 0.50 or less	+0
Any modifications that result in increased engine compression ratio (including shaving the head or decking the block to factory specs): >0.50	+3
Any modifications that result in increased engine compression ratio (including shaving the head or decking the block to factory specs): >1.0	+6
Any modifications that result in increased engine compression ratio (including shaving the head or decking the block to factory specs): >2.0	+10
Any modifications that result in increased engine compression ratio (including shaving the head or decking the block to factory specs): >3.0	+15
De-stroked engine	+4
Added dry sump oil system	+7
Added dry sump oil system if motor is lowered from OEM location	+14
Modification or porting of the exhaust manifold	+2
Aftermarket or modified header	+2
Non-OEM or modified exhaust piping, resonators, or mufflers downstream from the header, exhaust manifold, or turbo.(does not include catalytic converter removal/upgrade)	+2
Removal, upgrade, or modification of catalytic converter(s)	+1
Non-OEM sequential (semi-automatic) or dog-ring (non-synchromesh) transmission (includes altered gear ratios)(does not include automatic transmissions utilizing a torque converter)	+7
Upgrade number of forward gears in transmission or altered gear ratios	+3
Final drive ratio modification	+3
Added paddle/electronic shift	+3
Added limited slip differential or welded/locked differential	+3
Changed or modified limited slip differential (or welded/locked OEM LSD)	+1
Added traction control (no points if proven disabled during competition)	+3
Relocation of engine/transmission between 1 and 10 inches of the OEM location (note: Relocation of less than 1 inch is not assessed points, and more than 10 inches is not permitted without the approval of the NASA-X National Director.)	+7
Modification/upgrade from a fixed to a floating rear axle	+3
Modification/upgrade/replacement of flywheel or torque converter with any lightened or non-OEM part (note: balancing/resurfacing a stock flywheel is still +1)	+1



Suspension / Brakes / Chassis

Modification	Points
Non-OEM shocks/struts/dampers with an external reservoir or more than two ranges of adjustment—must still take points for springs below (example: compression (bump) and both high & low rebound adjustments)	+10
Non-OEM shocks/struts/dampers with a “Piggy Back” external reservoir (fixed reservoir without a connecting hose) OR with shaft diameter 40mm or greater—must still take additional points for the springs below	+7
Non-OEM or modified/re-valved shocks/struts/dampers (all others)(springs not included)	+3
Changing the mounting orientation/design of the OEM shock and/or spring perch in order to invert the shocks/struts (includes non-OEM inverted shocks/struts)	+1
Non-OEM or modified coil springs, leaf springs/spacers/brackets, or torsion bars	+2
Conversion of torsion bar/leaf spring suspension to coil spring and strut/shock suspension	+2
Add, replace, remove, or modify anti-roll bars or end links (“sway” bars—front, rear, or both—may have spherical joints on the end links and/or relocation of the mounting points without additional points assessment)	+2
Non-OEM driver/cockpit adjustable sway bar or suspension settings	+4
Replace or modify control arms (other than plates, shims, slots, or eccentric bolts/bushings for simple camber/caster adjustment only) or RWD/AWD rear trailing arms (may have spherical/metallic joint for the connection to the spindle/knuckle)	+4
Non-OEM rear control arms on FWD vehicles (for stiffness and wheel alignment only, no change in suspension mount or pick-up points from stock)	+1
Non-OEM rear trailing arms on FWD vehicles (for stiffness only, no change in suspension mount or pick-up points from stock)	+1
Using the alternate control arm mounting location on cars equipped OEM with multiple choices (example: to increase track width)	+6
Changing the orientation or design of an OEM mounting point or pick-up point of a control arm for a panhard bar or trailing arms	+1
Replaced or modified K-members that change the location of the lower control arms	+8
Tubular K(cross)-members that do not change the location of the lower control arms	+2
Relocation of front suspension mounting points	+6
Relocation of rear suspension mounting points	+6
Bump steer kits or shimming of the steering rack	+2
Alteration of ball joints/dive angles	+2
Add panhard rod or Watts link (regardless of whether or not the Watts link replaces an OEM panhard rod or the panhard rod replaces an OEM Watts link) (may have spherical joints without an additional points assessment)	+4
Replace or modify an OEM panhard rod or Watts link (may have spherical joints without an additional points assessment)	+2
Add torque arm	+4
Replace or modify an OEM torque arm	+2
Metallic and/or spherical-design replacement suspension bushings (except for pillow ball camber plate joints, sway bar end links already assessed points in 7) above, control arm spindle/knuckle joints already assessed points in 9) above, and panhard rod or Watts links already assessed in 20) or 21) above.)	+3
Add front lower stress/arm brace (two attachment points maximum)	+1
Add front strut tower bar (two attachment points—bolted in or as component of the cage)	+1
Add rear strut tower bar (two attachment points—bolted in or as a component of the cage)	+1
Add a third (or more) attachment point to front or rear strut tower bar (or replace an existing/OEM three point bar)	+1
Add or modify other chassis stiffening devices or fabricated parts (such as lower strut braces or lower arm braces (with greater than two attachment points), subframe connectors, subframe braces, subframe mounts/bushings, etc)	+3
Non-OEM, modified, or relocated brake calipers and/or brake caliper brackets	+2
Seam or stitch welding of the body/chassis	+5
Increase in track width greater than four (4) inches due to non-OEM axles, control arms, brake rotors/hats, wheel spacers, hubs, wheel offset, and/or camber adjustment (measured from the inside of one tire to the outside of the opposite tire at ground level— averaging the measurements in front of and behind the contact patch to negate the effect of toe)	+6



Roll Bars / Cages

Modification	Points
4- point roll bar and 6 or 8-point (two main hoop, two rear brace, two front hoop, and either two front firewall or foot well optional mounting points) roll cage designs constructed per the NASA CCR may be utilized without a NASA-X modification point assessment. Additional bars and/or attachment points within the driver’s compartment that exceed the allowances in the CCR are also permitted.	+0
One or more bars that penetrate the front bulkhead/firewall	+2
One or more bars that are welded to the chassis (directly or with a plate) anywhere farther than 6” from the end of one of the above 6 or 8 listed tubes where it terminates at a plate	+2



No-Points Modifications

Modification	Points
Rolled fender lips	+0
Flared fenders	+0
Sun/moonroof removal and cover roof hole	+0
Battery replacement/lightweight battery/dry cell	+0
Air bag removal	+0
OEM jack and spare tire removal	+0
Floor mat removal (required)	+0
Wheels, studs, spacers, wheel bearings replacement/upgrade, hub modification/replacement, all with less than 4 inches of total track width gain, also axle modification or replacement (unless otherwise assessed points above)	+0
Simple camber, caster, and toe adjustment by any method that does not alter suspension mounting points (unless the modification used is otherwise assessed points above) - such as control arm, ball joint, and relocated mounting point modifications). Slotting of the OEM bolt holes and removal of material from the top surface of the OEM strut/shock tower to the extent necessary to allow simple camber/caster adjustment is permitted. Bolt on camber/caster plates are not assessed points.	+0
Ride height adjustment (must still take points for springs and torsion bars above)	+0
Air filter upgrade (without modification of the air filter housing or air intake system)	+0
Radiator upgrade/shrouding/fascia modification (drilled or cut holes/slots) that only provides increased airflow to the radiator or oil/transmission coolers (without aerodynamic or engine air intake improvement)	+0
Starter motor replacement	+0
Alternator replacement (must be able to sustain vehicle operation without a battery	+0
Oil systems and coolers other than added dry sump	+0
Motor, transmission, and differential mounts and inserts/bushings, replacement/upgrade or modification (with up to 1 inch of relocation of the motor/transmission)	+0
Engine rebuild with head shave, block decking and 0.020” overbore—provided that compression ratio is not increased by more than 0.5 and displacement is not increased by greater than 1.49%. Forged pistons and internals are legal; however, points must be assessed for de-stroking, and/or increased displacement and compression ratio if greater than the limits listed above. (Note: 0.020” overbore with OEM rods and overbore pistons will yield an increase in displacement of approximately 1.1% for most engines.)	+0
Engine balancing and blueprinting	+0
Spark plug wires, plugs, coil, ignition replacement/upgrade	+0
Turbo blow-off valve upgrade, modification, or addition	+0
Removal of the engine balance shaft and/or balance shaft drive mechanism	+0
Replacement of clutch assembly with aftermarket or modified parts	+0
Fuel: Any grade of commercially available unmodified gasoline or diesel--all octane levels of retail available race gas are permitted. No “home brewed” methanol/ethanol/alcohol mixtures are permitted. Methanol injection systems are illegal. Fuel additives are prohibited. Retail available E-85 is permitted	+0
Brake duct addition or modification, including electric fans (water sprayers are illegal). Two holes may be cut or drilled out of the front fascia for brake air ducts. Any hole providing improved intake air to the engine will be assessed one (1) point.	+0
Non OEM brake pads and rotors	+0
Brake lines, boosters, proportioning valves, and master cylinder modification or replacement	+0
Emergency brake removal	+0
Non-metallic replacement suspension bushings	+0
Steering wheel replacement	+0
Mirror addition, removal, or replacement	+0
Gear shifters and shift knob replacement/upgrade	+0
Seat harnesses	+0
Maximum of two hundred and fifty (250) lbs. of added ballast—All ballast must be of solid material (no fluids or shot pellets) and safely secured in any location on the vehicle approved by NASA technical inspectors. The preferred method is to use at least one (1) 3/8-inch grade- 5 bolt, two (2) “fender” washers and a locking nut system for every fifteen (15) pounds of weight.	+0
Data acquisition systems and/or telemetry	+0
Non-OEM driver’s seat	+0
Non-OEM front passenger seat	+0
Relocated battery	+0
Adding a hardtop to a convertible and/or removal of convertible soft top/frame	+0
Shock tower reinforcement plate (to strengthen tower shock mount location only--no bars)	+0
Shock mount replacement/modification (only if already taking points for both shocks and springs)(may raise or lower mount location up to two (2) inches if no horizontal movement.)	+0
Accelerator, brake, and clutch pedal modification or replacement	+0
Drive by wire to cable throttle conversion (throttle body must remain identical to OEM in both size and shape to avoid a +2 throttle body assessment)	+0
OEM ECU/PCM reprogramming via reflashing or replacement/aftermarket ROM chips or simple ROM boards (the OEM ECU/PCM box/housing and hardware must be used)	+0
SAFC or VAFC (Super Air Flow Converter/VTEC Control Air Flow Converter)	+0
Non- OEM sensors or alteration of sensor inputs (such as non-programmable MAF or MAP voltage “clamps”)	+0
Steering rack replacement or modification without geometry change (ratio changes)	+0
Non-OEM valve springs and retainers	+0
Ignition timing adjustments	+0
NACA ducts, air ducts, or air hoses placed in a side window frame solely for purposes of driver cooling	+0
Front wing/vent window removal and replacement with Lexan	+0
Headlamps, headlight covers, and fog lights may all be removed, and the holes may be covered with material that replicates the shape of the OEM light/cover, leaving the shape of the OEM fascia intact. Uncovered holes may be used for brake ducts. Any hole providing improved intake air to the engine will be assessed one (1) point.	+0
OEM air conditioner system removal with or without A.C. delete pulley	+0
ABS (anti-lock braking system)--Only OEM systems offered specifically for the car Model as a factory option. No OEM systems offered for a different car model or aftermarket systems are permitted	+0
EGR, smog pump, charcoal canister and associated vacuum line and hose removal	+0
The addition of a second fuel pump inside an OEM fuel tank, serving only as a transfer pump to help prevent fuel starvation, that is not connected to the fuel line providing fuel to the engine in any way, and does not increase the maximum fuel flow or pressure provided by the OEM fuel pump	+0
Add, replace, or modify front fascia or air dam	+0
Add, replace or modify a single front splitter/spoiler/wing/foil	+0
Add, replace, or modify rear wing or spoiler	+0
Add or modify canards/winglets	+0
Add or fabricate any flat bottom/belly tray	+0
Add rear diffuser, replace or modify OEM rear diffuser, rear bumper cover, or rear “fascia”	+0
Add rear vertical panels in any location	+0
Add or modify side skirts	+0
Add vortex generator to roof, rear window, or rear deck lid	+0
Front side window frame air dams/diverters (driver and/or passenger side)	+0
Tire pressure monitoring systems (TPMS) (Pressure release valves are not permitted.)	+0
Header and exhaust piping external wrapping, coatings, and/or paint. (The original OEM identification markings must still be legible on all exhaust components that are not assessed points.)	+0
Oil catch tanks/cans	+0
Valve cover replacement or modification	+0
Carburetor jetting modification	+0
Carburetor vacuum port blocking	+0

General Advice

For the first time autocross competitor, consider the following list of items that may be beneficial to take along.
• Toolbox
• Torque Wrench
• Tire Pressure Gauge
• Rechargeable Electric Tire Pump (Increase tire pressure to maximum noted on tire sidewall, and adjust up or down from there)
• Liquid Window Chalk or White Shoe Polish (To mark tire shoulders and observe tire rollover to determine if tire pressure should be increased or can be decreased)
• Painter's Tape / Masking Tape (For attaching car numbers)
• Pen and Paper (To take notes of car adjustments)
• Folding Chair
• Umbrella (Good for rain or sun)
• Poncho or Rain Coat
• Sun Screen
• Wide Brimmed Hat
• Comfortable Clothing
• Comfortable Shoes
• Spare Comfortable Shoes And Socks (In case of sudden rain or in case the first pair get uncomfortable)
• Spare Jacket, Long Pants, Shorts (In case the weather changes)
• Bug Repellant
• Leather Palm Gloves For Steering Wheel Grip
• Narrow Sole Shoes For Driving
• A Good Night Sleep


Participating in an autocross does not require that any safety equipment be installed in the vehicle. It is required that the driver wear an approved racing helmet, but most clubs have loaner-helmets available for participants who do not own a helmet.
But the vehicle will go through a safety inspection, which will check the following:
• Battery Tie Down Strap (To prevent the battery from falling out of the vehicle. This can be a serious issue for older cars, as the tie down strap may have been discarded or might have rusted in two, and new replacement tie down straps are no longer available for Geo Storm and Isuzu cars.).
• Throttle Return Spring (Not usually a problem).
• Wheel Bearings (Normally tested by shaking the wheel and tire while the car is resting on it, which will only reveal the most completely failed wheel bearing. Storm owners will want to test the front wheels by raising the car on a jack and shaking the wheel and tire when it is free of the ground. Any play in the bearing should receive immediate attention and replacement, because the normal failure is due to the bearing spinning on the hub, removing metal from the hub, and rendering it unusable.).
• Remove All Loose Items From The Inside Of The Vehicle (It is surprising what will roll under the brake pedal or hit the back of the driver's head while driving at an autocross.).


For those interested in improving their autocross run times, the following is suggested before investing in any go-fast-goodies:
• A Racing Harness (Securing the driver in the driver's seat allows the driver to devote their full attention to the task fo driving, without the distraction of bracing themselves to keep from falling out of their seat).
• Autocross Driving School (Provides expert advice and the opportunity to practice for a much longer duration of time than the 3-6 runs lasting a minute, at an autocross event.