I will wait to reserve judgement but, traditionally a Rotrex style s/c will develop power lower in the RPM band were Vortec is more top end/less response (not a bad thing depending on what you want). My guess is that this kit is going to be cheaper than the Stillen one. It doesn't have the extra manifold, lines, pump and cooler. I'm sure it will be lighter also. If GTM nails the tuning and it works well I think a lot of people talking shti are going to be
and all will be forgotten...