1-3/4" headpipe steps up to 1-7/8" into the collector to increase flow and improve performance 4" muffler body with billet end cap (24" long) Removable spiral-core louvered baffle included Includes heat shields and mounting hardware 12 mm and 18 mm O2 sensor ports Made in the U.S.A.. EXHAUST 2:1 RR C 49C M8FL