pipe silencer???

[aor@gci.net]

I was traveling recently & picked up a dirt bike magazine - MX or something like that - I forget the name. In one of the product review sections was some kind of cylindrical devise that attached to your exhaust pipe. The claim was that it did some sort of acoustic hockus pokus which helped quiet the pipe. Been trying to locate - magazine with no luck - I forgot name of product. Does this ring a bell with anybody? Do you know anything about product?