i wouldn't recommend heat wrapping the expansion chamber. generally speaking, two stroke engines are very susceptible to changes in exhaust temps, and wrapping the pipe will cause it to run like crap and lose a good bit of power. i know a few guys who've experimented with wrapping their pipes on various dirtbikes as a way to quiet the classic two stroke pinging while riding on private land and all of them reported major power loss and even after rejetting the carb they just couldn't get the bikes to run well.