Dan - I think yer talkin' about an exhaust cutout... somewhat common on street rods (but illegal heheh) which if installed after an expansion chamber on a two stroke - but before the muffler(s) on either a 2 or a 4 stroke - allows you to open a bypass to achieve full flow (and noise) or close it for that "stealthy" approach.
If I thought there'd be enough of a gain on these lil bikes - I'd do it meself with a ball valve, cable and a thumb shifter...
hmm...
If I thought there'd be enough of a gain on these lil bikes - I'd do it meself with a ball valve, cable and a thumb shifter...
hmm...