RE: Does exhaust diverter decrease power??
I used them from day one on most of the two strokes i have owned. As for robbing power?? Nothing I have ever noticed but I'm sure they do to a small degree. My trick for keeping them on is to run a bead of JB Weld around the muffler tip so the extension has a lip to be tightened around. I only have one two stroke engine being used at the moment and it has the deflector on it. Due to engine location it doesn't help deflect the snot very much. This is a bigger engine though, an SK .90 but I even use them on the OS .40 LA when I run the engine on a trainer.