4" reverse-cone megaphone muffler body with matching billet end cap1-3/4 head pipe steps up to 1-7/8 into the collector to increase flow and improve performanceRemovable spiral-core louvered baffle included Features hand MIG welding18mm and 12mm O2 ports with adapters and plugsIncludes mounting hardware and full heat shieldsMade in the U.S.A.