do not waste time on the stage 4 stuff. it's basically for show.
the stage 3 stuff is fairly proven, but for the money youre spending you really should just go custom with the heads and cam. youll end up with a much more stout setup in the end instead of trusting a vendor setup to be what you want. besides, their heads cost way too much and you can cut that in half (or more) by getting your heads done locally at a motor shop.