Supertrapp 628-78055 Internal Disc Series Slip-On Exhaust 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 Technology. They feature a rebuildable core and packing to help minimize your maintenance. Internal Disc Series are compatible with five end cap options.3" chrome slip-on mufflers in tapered, fishtail or turnout styles (except where noted).End caps are interchangeable with any 3" cap (except where noted).Each muffler includes 12 internal discs.