You don't "Have to"... you won't max out the flow till full throttle per say.. kind of like adding K&N filters.. every little bit along the way helps. And that "price" was just a typical average from my research on parts. In real simple terms.. you've got a 3" hole sucking through a 2 3/4" opening.. really would only come in to play at full throttle with the butterfly wide open for that full 3" to suck through.