Supertrapp 628-71570 Internal Disc Series Exhaust System Internal Disc Series are a beautifully styled, conventional-looking, chrome muffler. They provide 10 - 15% horsepower gains. Internal Disc Series Slip-Ons and Systems utilize the patented Tunable Disc TechnologyInternal Disc Series are SAE-J2825 sound compliant. They feature a rebuildable core and packing to help minimize your maintenance. Internal Disc Series are compatible with five end cap options.Features SuperTrapp tunable 3" internal disc muffler with fishtail end cap.Durable steel construction with brilliant chrome-plating.Eighteen, 3" discs are also included:Add 3" discs to increase