The Black Mamba decat downpipe is the perfect performance upgrade for the BMW 240i G42, 340i, and 440i G2x with the B58 engine and OPF. Manufactured from premium T304 stainless steel, this 4″ (100mm) to 3″ (76mm) diameter downpipe features mandrel bending and TIG hand welding for a precise fit. With its high-flow structure and optional anti-thermal heat shields, this downpipe is the best value for your money, designed to minimize heat in the engine bay and maximize power output.Direct bolt-on installation 4″ (100mm) to 3″ (76mm) diameter pipe 100% T304 stainless steel construction Optional anti-thermal heat shields TIG Welded for strength and durability Aggressive exhaust tone Lifetime warranty.