Here is what you can and can not do in Stock classes.
TIRES
You must run stock size wheels but they do not have to be STOCK wheels. beleive it or not, the smaller diameter wheels seem to work best with short side wall tires. Hard to beat that lower CG. You can run with DOT approved racing tires. When buying tires, look for the lowest treadware ratings. Around 170 would be good for racing but ware out quick on the street. They can be any size that will fit on the rim correctly. Most people keep their set of racing tires and rims off the car and change them when they get to the track. If you must use street tires, inflate them to 38 to 40 psi. Deflate them to normal pressure before returning to the street. You must remove hub caps. Be sure you have secure wheels and no broken lug studs.
REMOVING THINGS
You can not remove anything that is bolted down. The spare tire is the exception. You may need to try your car with and without the spare to see how your balance works. You may want to try different levels of fuel in the tank. Half a tank of gas may not work as well as 5/8ths, etc... You can not remove your airfilter unit. You may remove the filter. You can not remove seat belts but, you may add a five point harness. You can not add any braces, strut tower or otherwise, unless it came on the car originally. Take out that booming stereo box speaker system before you leave the house. It's just dead weight anyway and if it's loose, they will make you remove it. Where do you keep that loaded box at the track? You don't. They don't have places to keep stuff like that so they get jacked! They will leave your tires alone though. Weird huh?
ADDING OTHER THINGS
You may add any kind of shocks you want as long as they mount in the stock location and require NO mods to install. Install the best brake pads you can afford. They will check to make sure you have good brake pedal pressure before your class runs so do not show up with poor pedal pressure. The tires, brakes, and shocks will be your best investments and will lower your time the most as far as parts go. There are other small things that the rule book will cover which you must buy before you can compete at most events. They usually sell them there at the race. Another thing is a helmet. If you don't have one, they usually have loaners.
The best way to win is seat time. You will find that the fastest car doesn't mean poop at these events. Sure it doesn't hurt to have more power but skill is where it's at and when you go to race, go to learn. Ask questions and go to as many events as you can. It will also make you a safer, smarter street driver.
Good luck and have fun!
