Quote:
Originally Posted by JSH
When you say cat deletes, do you mean hi-flow cats or no cats?
Regarding hp, it's my understanding that the stock cat back has a crimp in each pipe at the axle. If this crimp is significant enough to cause any back pressure, then it theoretically reduces hp since this engine should perform best with a scavenging effect or negative pressure at the exhaust valve/port. If said crimp does not cause ANY back pressure then an axle back system would be sufficient for me.
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Cat delete means exactly that...the Cat's are deleted. I have the CA bolt-in delete pipes. I didn't go headers because of the added noise and for reasons I'll explain below.
Far as the crimp section...It's been proven that the NPP cat back is not restrictive until you get north of 800whp. CSP did a dyno comparison when he had his H/C ZL1 and gained like 3-4whp.
The exhaust mods that gain power are deleting the primary cats(biggest bottle neck), then headers. Headers with high flow cat's are marginally better then factory headers with cat deletes. Catless 2" headers are worth about 20whp over stock headers with cat delete's on a 7-750whp car. I am sure the gains become greater the closer you get to that 1k whp mark.