S&S Mk45 4.5 Cutlass Slip-On Mufflers For Harley Touring Mk45 Slip-On Mufflers are the result of decades of riding, racing and tuning. Combining both a stainless-steel perforated core baffle with Race-TEX cartridge packing, they create a deep rumble and improved horsepower and torque, all while adding a unique look with styled aluminum end caps. Features: 7 horsepower gain Stainless steel baffle with Race-TEX cartridge packing Removable dB Reducer (J2825 compliant)