Sthus40mm Half Moon Silencer Muffler Exhaust Black For 49cc 60cc 66cc 80cc 2-Stroke Engine Motor Motorized Bicycle Bike

I have one. It doesn't hit my frame, and it definitely adds power over the stock pipe. It is really loud. You can get these for under 25 bucks. https://www.amazon.com/Sthus40mm-Silencer-Muffler-2-Stroke-Motorized/dp/B07BC9Z1T7/ref=sr_1_19