The results seem pretty consistent on midrange gains for un-tuned vehicles. Some people seem to be reporting what appears to be some overlap between the manifold's gains and tuning gains (i.e. they can gain the same midrange from either just tuning or just the manifold, but no additive effect when tuning with the manifold in place). But others claim to have tuned w/ the manifold and still gotten gains from it. I guess it depends who does your tune and how they do it.
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