For SCCA rules there are alot you can do to a typically car, but the SHO has no real aftermarket suspension parts. so there isn't much we can do. If i did the lowering springs and/or a tune that would put in a class called SMS which is fully of highly modded M3s, STs & Evo. In that class no matter what power i had i couldn't be competitive so thats why i'm running a stock class. The car is actually competitive in RTA. I ran against at STi this past event who had better tires and only lost to him be less than 2seconds, so i'm happy where i am.
If i didn't care about the rules i could cheat and get tuned. Most people don't know enough about the SHO to tell, but wheres the fun in that. Plus i am not lacking for power with my PP car now so more power wouldn't help all that much.