D&D Performance Exhaust manufactures custom aftermarket exhaust systems for Harley Davidson Dyna exhaust systems. Each exhaust system features a deep, boomy sound that is full of character. All full system Dyna exhausts are equipped with heat shields, gaskets, bolt kit, and baffles. Our aftermarket Dyna exhausts are also designed and dyno tested in our facilities. Performance increases are around 8 to 10 percent with the proper tune. All Harley Dyna systems are designed for closed course racing applications only. Not for use on pollution controlled vehicles.