Quote:
Originally Posted by Blackdevil77
I could of sworn I read that they don't gain much since the factory manifolds are much more efficient than they used to be, using a Tri-y design etc.
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On a SS, 1 7/8 arh headers with cats to stock NPP, MSD intake, roto fab gained +46whp. Gains would be even more with a boosted LT4 minus the MSD of course.