Slinger, Exactly! Shaka, Not $90.00 worth. Make one from an old P.A. horn or a speaker cone, and a piece of anything scrap. The concept is to eliminate the pulsing of the expansion chamber on a 2t, or the cycle of the valves on a 4t. The reality is the pulse is still there but the jets work more efficiently both before, and during the "cycle". I have never run one on any bike/scoot/engine. It's just something I have heard of from others. I guess the finer the tune on your engine the more noticeable the effect would be.