Whats there needs to be is a standardized catagory list that is adopted by all clubs, event promotors, etc. Like MPAA movie ratings. But, to keep things fair, a single deviation from stock should put you in a modded catagory. A person could have an expensive paint job and wheels and nothing else, yet still fall into a stock catagory. So the modded catagories should be based on 3 or maybe 4 groups.

Lightly modded. 5 or less simple things, nothing more major than wheels/tires. Stock paint and body parts.

Mildly modded. 6 to 10 mods including more striking visual mods such as simple stripes, painted or vinyl, simple flames, simple body kit. Single color change with no "extravagant" paint processes such as flip paint, custom metalflakes or candy colors. No body part fabrication.

Heavily modded. More than 10 mods of any kind. Multi color change. Flip paint, candies, custom colors, mild body fabrication such as shaving, nosed, decked, chopped, channeled, frenched, cut windshield frame.

Unlimited. Anything goes.