diameter/length are critical in header primary tubes for pressure wave tuning/scavenging & all that good engineering stuff but after the collector flange you want NO restriction/back pressure. With manifolds same deal you want NO backpressure. I firmly believe that people who claim to have slowed down after adding a larger ex/tail pipes/muff system also changed something else at the same time which actually is what caused the slowing down.


live every 24 hour block of time like it's your last day on earth