Actually Dan, you might not be giving your product enough credit...

Various studies have shown that a product like yours can in fact add a few fps to an arrow. It's widely thought that the cleaner release provided by a string suppressor is the cause, as it stops the string at brace. It doesn't allow thestring to "pull" ever so slightly on the nock as a bowstring without a suppressor travels extremely far past brace, and that's where some have surmised that the string returning to brace isactually counter-productive at that point.