fmf power core 4 muffler w/stainless steel header fmf the mini powercore 4 is the best bang for your buck performance bolt on for your mini closed course moto muffler features a hi-flo stainless steel core and formed end caps aircraft grade aluminum canister and a durable stainless steel header pounds lighter than stock and you will swear the motor has been bored and stroked with the first twist of the throttle <br>