I just received the inverted Bisson muffler that is going on an MVVS 1.60 gasser in a H9 Cap. there is no way this muffler will fit inside the cowl The exhaust pipes that point straight down are way to long. does anyone know if I can trim these about 1/2" shorter without hurting performance. Thanks.

SPLAIS: I TRIMED ABOUT A 1/2 IN OFF MY BISSON PITTS MUF ON MY MOKI AND IT DID NOT CHANGE ANYTHING. I HOPE THIS HELPS.

Just be sure not to change the backpressure to the tank by doing so. My Bisson muffler has crimped ends to create some backpressure. If I cut off 1/2" I would remove the crimp. You can always epoxy in dowels with JB weld and drill them out to a desired opening for added backpressure if you still have to. Good luck
Rick

As he's using a gas engine with a pumped carb, there is no muffler pressure supplied to the tank.

Back pressure helps 2 strokes run cool. Too much loss of back pressure can lead to an overheat problem. I'd be cautious about cutting if there seems to be a crimp in the end. I'd call Bisson.