If you don't track your car much, buy a VT1-550, there's plenty of power and it's relativly cheap, run 93 of 94 octane if you have access to it, it makes a BIG difference in power!! I have the older VT1-535 kit with stock cats and run 94 all the time, my car is manual and I beated a Gallardo on the highway yesterday and was pretty much equal with a new M5 2 days ago! I'm installing test pipes tomorrow morning, and that should be it for me, unless Roman/Ess offers me to upgrade my kit to a 550 for free!
Seriously I say that a lot because I believe it, the VT1 is all you need for the street!! A 550 kit with 93-94 octane and test pipes should put you around 600hp, that is just perfect for this car I think!
