Modified Category


If your car does not meet all of the Stock Category qualifications, you may qualify for the Modified Category. The Modified Category is intended for modified, but streetable cars on street tires.

Qualifications for the Modified Category are minimal:

  • Tires must be treadwear 140 or greater.
  • Cars must be street legal in the State of Florida, but registration and insurance is not required.
  • The intent of this category (except Open Modified) is that cars should not be so extensively modified that they could not be returned to stock. In general, cutting & welding is bad, bolt-on stuff is good; looking like a stripped race car is bad, looking like a complete street car is good.

Modification Limits

Modifications for classes M1, M2, M3 and M4 are unlimited except for the following:

  • Body & Interior
    • Exterior body panels must not be removed unless factory-optional (such as t-tops or convertible tops). 
    • Bolt-on panels may be modified or replaced. Changes in appearance or style are acceptable.
    • Non-removable fenders may be cut only as neccessary specifically for the purpose of fitting fender flares or body kit items.
    • Other non-removable panels may only be modified by the drilling of holes provided those holes are no larger than required, and serve a valid purpose. (mounting body kit or accessory items, routing wires, etc)
    • All factory glass or equivalent (OE style safety glass) must be present.
    • A mostly-complete interior is required. Missing minor trim or a panel or two is acceptable, as is removal of the back seat.
  • Lightening
    • Parts must not be removed if removal will affect the appearance of the exterior or interior of the car. 
    • Parts must not be cut off to permanently remove them.
    • The shell and frame of the car (the main structure to which other parts are affixed) must not be cut, drilled or altered for the purpose of lightening.
    • Bolt-on parts may be removed in accordance with the rules above.
    • Bolt-on parts may be replaced with lighter or lightened parts.
  • Bracing
    • Braces must not be welded to the car.
    • Any bolt-in bracing is allowed.
  • Drivetrain Swaps
    • The shell and frame of the car (the main structure to which other parts are affixed) must not be significantly altered for the purpose of fitting drivetrain components. Returning the factory components to the car should always be a simple bolt-in process.
    • Any bolt-on part including subframes and mounts may be modified or replaced as required. 
    • The intent is to allow mostly bolt-in engine swaps.
  • Factory Forced Induction
    • Modifications are restricted with the intent of keeping these cars on par with the normally aspirated cars in their class.
    • Certain modifications will bump these cars up to the next higher class. (see Class Progression below)
  • Nitrous Oxide – Our insurance rules do not allow a Nitrous bottle to even be present at our events due to the bottle pressure and safety concerns. Leave your bottle at home!

M0 (Open Modified) Rules

The Open Modified class (M0) is for exotic cars, and cars that exceed any of the above limits, but are otherwise street legal and on street tires. Cars that bump up from M1 also go to M0. For safety, doors, hood and a complete firewall are required for ALL Modified cars.

Tube frame and kit cars are allowed in Open Modified provided they have a minimum of two seats, are fully street legal, and meet all safety requirements.

M4 Class Rules

Cars in M3 may “bump down” to M4 if they have a tire size no wider than 225, and have no limited slip differential other than a factory Viscous type.

Class Progression

Certain modifications will result in a car being classified in a higher class than normal.

  • Bump up one class for adding forced induction (turbo or supercharger)
  • Bump up one class for any of the following on a car with factory forced induction:
    • Any change to the Turbo or Supercharger
    • Any change to Fuel Injectors or Fuel Pressure
    • Any added Injection of any type (water, methanol, fuel, etc)
    • Changes to both the Intercooler AND Boost Control — can do either one, but not both. (Boost Control includes changes to electronic boost control. Intercooler does not include piping.)
    • Any internal engine modifications
    • Any change to gear ratios (transmission or final drive)
    • (Intake, exhaust and computer tuning are permitted)
  • Bump to donor class OR up one class (whichever is higher) for a significant (+25% HP increase) engine swap that is not a common bolt-in swap that results in a factory-available (US market) configuration.
  • A car will only be bumped up one class, bumping is not “stacked”. An engine swap AND adding a turbo would be a single class bump.

Identifying Your Class

First, find your car on the class list. As many other clubs do, we share the SCCA Solo car classification lists because they are thorough and regularly updated with new cars. We use their “Street Category” class lists as the basis for our modified classes.

Street Category Car List (pdf)

Use your SCCA “Street” class to choose your FAST “Modified” class.

  • M0 – Open Modified Street Tire (SS, bumps and unclassed but streetable cars)
  • M1 – Modified Street Tire 1 (AS/BS and bumps)
  • M2 – Modified Street Tire 2 (CS/DS/FS and bumps)
  • M3 – Modified Street Tire 3 (ES/GS/HS)
  • M4 – Voluntary bump down from M3 (must meet requirements)

NOTE: If your car is listed as “excluded” in the SCCA list, but is not an obviously unstable and top-heavy vehicle such as a stock SUV, off-road pickup, or minivan, contact us. We may allow it in Modified, especially if you have significantly improved the suspension and/or reduced the ride height.

Last update 9/2016 (changes in red)