He builds each intake based on the application. I furnished him with my cam and head specs, gear ratios, and estimated HP and boost levels.
The intake you see would probably work very well on a strong N/A setup with N2Ox, but he'd probably tweak the design a bit. The manifold not only flows better than stock, it more evenly distributes the air. The stock manifold sucks for distribution, making the front four cylinders run lean (so the whole mix has to be set rich to compensate). You can also have nitrous ports welded into the runners for direct port injection.
Any engine, regardless of how it's equipped, will benefit from a custom manifold. Hell, the Viper engine took a performance hit going from the Gen II manifold to the Gen III manifold, so there's plenty of room for improvement even on an otherwise stock engine.
About 3,300.