Constructed of Stainless Steel with 1 5/8â€ tubing and features a true 4 into 1 merged collector for maximum exhaust flow. TIG welded for long lasting strength and good looks. This system includes a S/S V-band Muffler. Gaskets and hardware are in the box for easy installation. This is a competition system and cannot be used with heater boxes. Fits Split Window Buses (1967 and earlier).