Punchy little motor, Before firing it up I swapped all the way up to a 17T even then in first, It pulls well. wont wheelie or anything , but definitely has some power. The stock Motoped muffler will work with this engine it is 86cc, The stock muffler can take up to 88 cc, But it does run a bit warm all the way back at the muffler ( burned my hand a couple times) I highly recommend this engine :)