Well you will just get slaughtered in FSP. Those guys are spending all they can to the rules. I would suggest STS since that's the class made for us import guys.

First I would recommend a Novice school or Evolution School (http://www.autocross.com/evolution) held in your area. That in itself willl knock off lots of time cause the driver always needs fixing first before the car I attended my first Evolution School and knocked off about 2-4 seconds and now running in the top 5 in PAX

I would suggest a lightweight wheel: Kosei K1, Konig Heliums, Rota Subzeros, Rota Slipstreams, and if you want to spend more money SSR COmpetitions, RH CP-035s, Volk TE-37s.

Then get the Falken Azenis tires in 205/50x15".