Performance increases up to 15 percent with the proper tune on the bike!īelow are a few of our favorite D&D Exhaust Click Here if you want one. Every pipe is designed to increase low-end torque and horsepower. D&D’s testing is done with the Harley Tuner. All D&D Exhaust Systems are equipped with heat shields, bolt kit and baffles.Įach exhaust system is designed and dyno tested at D&D’s facility.