Keep the check engine light off with MagnaFlow HM Grade Federal/EPA Compliant Direct-Fit Catalytic Converter 50400. With features including free-flowing mandrel-bent tubing and highly corrosion resistant stainless steel construction easily install this spun body converter yourself using the proper tools no cutting or welding required. MagnaFlow's state-of-the-art metrology department uses the latest 3D scanning systems during research and development so you can be confident that your new part will fit and function like the original equipment. By replicating the OE spun body design the single laser fusion weld greatly reduces the possibility of a leak and our compact low-mass design also allows for greater thermal efficiency. Designed to fit the 2004-2005 BMW 645Ci 2004-2005 BMW 545i and more this direct-fit catalytic converter also interchanges with OE parts 18 40 7 522 555 and 18 40 7 522 571. Hardware is included to eliminate the hassle of working with corroded factory parts. This replacement part is designed to meet or exceed Federal emissions requirements set forth by the EPA complying with legal standards for OBDII Federally registered vehicles with Federal/EPA Emission systems.