Thanks for all of the replies and good info. After I posted I realized one of my statements may be misleading - "we don't care what you run or what you do to your car". It would probably make sense to still use the GCR as it is regarding suspension, safety, tire and wheel sizes (adjusted for power output), etc. Not make it a free-for-all like my original post may have sounded like. Basically, just remove the car classes and engine sections from the GCR and relpace those with a P/W ratio chart.

One of the reason I posted my question is that there seems to be a lot cars NOT listed in the GCR that would make decent racecars (for some people). Some of the most dominant cars in IT are 25+ years old (260Z, RX7's, etc..) and no turbo cars. I would think that the ability to run more cars (and turbo cars) would greatly increase the attractiveness of the class to new comers.

I read the monthly FastTRack and it's filled with rule revisions and such aimed at keeping a level playing field by micro management (BMW restrictors, compression ratios, weight penalties, ECU mods, etc..) Seems to me it would be far easier to class cars at the track with a scale and a dyno (measuring torque and HP) and not worry about what's been done to it as long as the rest of the car meets the basic GCR for suspension and safety.

Thanks again for the insightful input and being patient with me during my learning curve.

Scott