Originally Posted by 1slow370

The problem is it isn't actually a larger manifold, the CSA of the gtr runner is smaller, the runner is longer, and with the new lower the air has to fight some hard transition angles now too, as well as some very short profile changes in the runner. the gtr runner is not a huge oval it is actually just a straight tube that is cross sectioned at an angle where the flange is. It is a manifold designed specifically for boost and I wouldn't be suprised if you actually see losses on an NA car. It is designed to increase low and midrange to spool turbo's quicker.