Mild steel construction Features a muscular, compact stance with a deep, aggressive tone Exclusive three-step design; 1-3/4" header tubes flow into 2-1/2" to 3” stepped muffler bodies 2-1/4" Full Coverage Heat Shields Super Bung technology, compatible with 12mm and 18mm sensors Mounting hardware and installation instructions included Made in the U.S.A. Not compatible with models with side cases