Just found another that's cheaper and makes more power. Single turbo, though, so you cant brag about having twins.
http://www.turbo-kits.com/350Z_turbo_kits.html
365-385 whp
320-341 wtq
dyno chart
It's got a pretty turbo-ish powerband tho. If you're like me though, you love the feeling of hitting boost and the way it pushes you back in your seat
Edit: The turbo is good for 570 hp though, so if you wanted to build the engine and increase boost pressure down the line, it'd give you some room.