Stepped headers merge into a true reverse-cone megaphone muffler. 1-3/4″ headpipe steps up to 1-7/8″ into a collector to increase flow and improve performance. 4″ muffler body with billet end cap. Removable spiral-core louvered baffle included. Heat shields and mounting hardware included. 24″ muffler length. 12 mm and 18 mm O2 sensor port plugs included. Made in the U.S.A..