Had a chassie dyno done this morning to compare a before and after of installing the LS6 intake manifold in place of the older LS1 version.
Keep in mind the Cats are still functional.

Three runs were done in 4th gear, to 6,500 RPMs.

Before After
------ ------
375.2 HP 388.3 HP = 13.1 gain
357.6 Tq 349.5 Tq = 8.1 ft/lb loss

This of course were seen from the rear wheels.

I assumed to see a torque loss due to the larger mainifold.

This puts it around 450 HP at flywheel and maybe the car will launch a bit easier with a tad less torque at low end.

John