hi wat would be the best exhaust for my 69cc motor??? i need one that will produce good torque to get up hills and enough top end but also as quiet as possible, not to wake the neighbours at night. i have a moded expansion chamber on now , but it seems to lack top end big time and is too loud and currently vibrates loose all the time. the lead pipe to the expansion chamber is 12inch then 40 cm expansion pipe and then i put on the stock muffler at the end. all other parts are stock on my 69cc motor , i have also put on a boost bottle but it doesnt seem to affect it that much. can anyone help me out.?