I see your confusion.

The more efficient will be a larger remote unit something like this as used in turbo cars. This will allow for serious power 400+ HP very safely and allows long term racing like Time attack or track days. Something the small 2" cant do very well without overheating...


The unit that mounts under the manifold is the limited power one. There is just a limited amount of air flow it can offer and will limit power efficiency for high power applications. But will work fine for mild boost lower power. Those limits are yet to be determined... but definitely limited... don't think you will make 500hp with a small core under the manifold reliablywhile track racing...