Massive 4" non-tunable bodies Streamlined, internal tapered, billet aluminum end caps with recessed fasteners are preinstalled Inlets shaped for better flow into OEM headpipe as well as SuperTrapp True Dual Headpipes Provide a bold, strong power curve from mid-range on up with a significant horsepower and torque gain over stock mufflers Classic deep and heavy Kerker rumble is 5 dB over stock Made in the U.S.A.. MUFFLERS STOUT 10-16FLHT