Exhaust restriction and backfire? Oct 3, 2018 23:33:39 GMT -5 Quote Select PostDeselect PostLink to PostMemberGive GiftBack to Top Post by katt on Oct 3, 2018 23:33:39 GMT -5 Okay i put this one because its for both 150cc and 50cc since muffler is straight pipe no restriction at all enough flow for any engine size, only difference is different pipes used.