Blow Performance Exhausts Manufacturer of Performance Exhaust Systems for Harley-Davidson EVO & Big Twin 80ci-131ci Engines 1984-2017 & Milwaukee-Eight 107ci-131ci Engines 2017 - CurrentOur designs deliver increased performance and great sound as well as a variation in looks with our bonus 3 heat shield sets with every Killer Kit. We are committed to our customer's satisfaction and stand proud behind our product and service. Since our commencement in 2012 we have been dedicated to what we created for our biker communities worldwide. Blow Performance Exhausts are 3-Stepped Tuned Headers. From the exhaust port our header pipe merges into a larger diameter header pipe and then once more merges into an even larger diameter header pipe thus consisting of multiple step ups along the length of the exhaust pipe.Blow Performance Exhausts are designed for high RPM's and run at greatest performance without collector's, mufflers, or baffles. The first step helps prevent reversion, thus giving power at low RPM's. Steps placed further down the pipe create pressure drops in the flow of the gases, and increase power at higher RPM's. Our designs work with the exhaust pulse and give a broad power band on 80 ci -131 ci EVO & Big Twin, 107 ci - 117ci Milwaukee Eight Engines.Specifically designed and calibrated for pistonAnd currently Introducing Performance Exhausts for Milwaukee-Eight 107 ci to 117 ci Engines 2017 onwards.Our designs deliver increased performance and great sound as well as a variation in looks with our bonus 3 heat shield sets included in our Killer Kit Range.Blow Performance Exhausts are 3-Stepped Tuned Headers. From the exhaust port, our header pipe merges into a larger diameter header pipe and then once more merges into an even larger diameter header pipe thus consisting of multiple step ups along the length of the exhaust pipe.Manufactured for closed course competition. Please check your local EPA authorities for street use.