Logas is 100% correct here.
This misconception about less air=less fuel consumption is BS.
All these people are doing is creating an engine which is less efficient and therefore as a general rule more throttle angle would be required to attain more power=more load on the engine.
Why would anyone want an engine which is less efficient??
Throttle response and outright power are heavily compromised.
I can guarantee that if these engines were to be setup correctly with the correct instrumentation the end result would actually be a more efficient engine.