The wheels may take you out of Showroom Stock, the coilovers definitely will.
If you want to run in a TT Production class here are the rules (and a nifty little script to help you class the car):
http://www.renoscca.org/ttclass.php
The official class will depend on the weigh-in of the car, but I think the S2000 is pretty well smack in the middle of the TT-4 class, so weight probably won't change that.