You can use a larger sized t25 like a nissan silvia t25 at 7 psi would be ok on an ls motor.

You would probably be better off with a t3...

To be honestly with you the best way to go for some one without that much knowledge would be with a turbo kit specific for you're vehicle.

www.inlinepro.com = the best shit
www.revhard.com = ok
www.maxrev.com = ok

there are tons more.. including the greddy kits :-/