The larger manifold will make it a little bit more sluggish on bottom end, but it usually does not drastically change it on B-Series. However, if the head has a full race port on both intake and exhaust ports, that would cause a pretty good bit of loss in bottom-end power, especially if compression is low, or near stock and the engine is untuned. Just have someone who knows what they are doing check it out.Originally Posted by kpowerhatch





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