1-5/8 inches tubing featuring a true 4 into 1 merged collector. Tig welded for strength and good looks. The mounting flanges are thick for a great sealing surface. System includes quiet muffler with stainless steel tip. Complete with gaskets and hardware. NOTE: This cannot be used with heater boxes. Coating: None Raw SteelSideflow Exhaust System Compatable with Aircooled Beetle