Just picked this up for a song on CL. ($100) I've had a new Grubee Skyhawk 66cc kit sitting for over a month waiting to find the right bike. Wanted to go with something with a front suspension to sooth out that ride a bit. (2 past back surgeries). Also needed something big, as I'm 6'3" and 220lbs. And boy the XL frame on this is BIG! I'm wondering if anyone has experience with this expansion chamber from Bicycle Motor Works? Pretty cheap at $27.99 https://bicyclemotorworks.com/product/expansion-chamber-exhaust-muffler/ I used the muffler from the Grubee kit on another bike and was debating to try something other than a stock exhaust on this build.