I gained 300 or so RPM going from stock to the B&B muffler on a G-62, also gained much noise! Switched to a Bisson muffler for an OS 1.60 two stroke and lost 100 or so, but picked up a far nicer tone. The 160 muffler has the same mounting hole dimensions and exhaust port size as the G-62. I cut the necked down ends off of the muffler pipes to reduce the backpressure since gas engines do not need back pressure to pressurize the tank.