You can get a 9" open cone and make your self a cold air kit. Supercharger pulleys are cheap. And the rocker arms (1:9) ratio. with the rockers cold air and rockers my buddies 01 GTP went 13.0s. Check on www.zzperformance.com www.3800performance.com
and www.clubgp.com for more info
Exhaust work (ubend/resonator delete), intake with cone filter, and a smaller pulley are a good start. I have an extra 3.4 pulley for $50 if you are interested. Also check out RegalGS.org