4" reverse-cone megaphone muffler body with matching billet end cap 1-3/4" headpipe steps up to 1-7/8" into the collector to increase flow and improve performance Removable spiral-core louvered baffle included Features hand MIG welding 18 mm and 12 mm O2 ports with adapters and plugs Includes mounting hardware and full heat shields Made in the U.S.A.. EXH 2:1 C MID/MEG FL 17+