No offense meant but it sounds like you're in way over your head and want bragging rights to say you have a 500 hp car without really knowing what goes into it. Get ready for a lot of broken parts since it doesn't sound like you have plans of doing the other things that go along with this like axles, mounts, brakes etc. Go drive an is38 gti, I'm guessing you'd probably be pretty happy with 380hp. 500 gets really rowdy, can't really ever use that kind of power on the street anyways. Tire spin city unless you're using slicks.
My 2 cents, good luck.