Go find a the back issue of Chevy High Performance. They tested the LS1, truck, LS6, and FAST manifolds. The truck held its own against the LS6 and FAST only being down like 5-6 hp and same amount of torque. It made more than the LS1. That being said it is not the prettiest thing out there, but are you after looks or performance?

 

Anyone got that article they can scan or something? I'll host the pictures if you got them.

Were the LS6 and FAST close to each other in the article? If so I've seen independent results that said otherwise from a VERY well respected sponsor here that I would believe before any magazine article test .

 

Im looking for more power, the more the better. u know

 

Im looking in car craft magazine right now and they did a test on the GENIII 5.3l peek TRQ change from 384 to 392 and peek HP went from 437 to 458 when they swapped to the LSX FAST intake manifold. These test were ran up to 6800RPM so I guess if you plan on spinning that high then the LSX is a good swap!! But everywhere else on the map below 5800RPM, surprisingly, the truck intake manifold stood tall and was only off by 1-6 TRQ and about 2-7 on HP until right at 5700RPM the LSX FAST took a leep up to 16 More HP. Hope that helps some.