I am pretty sure you will get plenty of good sound advise here, but just in case...send this person an email (Reggie) rftibbe@flash.net. He has judged these events for a long, long time. More importantly, he is a great all around guy and is always willing to help.
Good luck,
Marty
...And this is what they have on their website...
STREET CLASS
The Street Class includes all vehicles with bolt-on aftermarket or dealer installed parts and/or accessories. The body may have bolt-on spoilers. Ground effects, fiberglass parts, etc. Any molding of these items moves entry to Modified Class. Paint may be of any color from any OEM manufacturer. Aftermarket candy, pearl, metal flake paint entries will be moved to Modified. Painted pinstripes, and taped pinstripes or decals and vinyl graphics are allowed. Judging Supervisor will classify custom work. Other items that move an entry to Street Class include bolt-on headers. Ignition wires, air cleaners, valve covers, continental kits, painted engine compartment, etc. Any molding of any type (including firewall, inner fenders, panels, etc) will move entry to Modified Class. Minor interior changes are allowed (seat inserts, minor truck or truck bed modifications, and bolt-in seats with stock-type interior). No custom interiors allowed. There will be no limit on the amount of bright items on the engine or in the engine compartment. See notes concerning dealer and factory-sold conversions in the Stock Class