Originally Posted by LSxJunkie
It doesn't. And who cares? You'll never feel 6hp.
I agree that its not enough to feel in the seat of the pants, but why wouldn't it make additional horsepower over the regular exhaust? I suspect that Chevy isn't claiming it because they haven't gotten around to certifying it.
I'll be interested to see what happens when somone puts an NPP on a dyno.