Lots of miss information swirling out there and I wouldn't trust a vendor who posts disparaging remarks towards potential customer on forums any further than I could throw em.
My stock Stillen with 8psi pulley, injectors, fuel pump etc makes 437 WHP on 100 octane gas. It runs like a champ. No belt slip, no rich or lean running, no detonation. One of the cleanest best kits I have ever seen. Others are a bit of a hodgepodge and are not CARB legal and they aren't willing to warranty kit like Stillen. Win to Stillen.
Hoopa Hillclimb 2012 - 370Z - YouTube
Mmmmmm sound so sweeeet
YouTube - Hoopa hillclimb 2012 - 370z
Bottom line if you are not worried about CARB you'd be silly not to go turbo on our cars? A non smog legal SC is a waste of space under the hood.