Keep the check engine light off with MagnaFlow California Grade CARB Compliant Direct-Fit Catalytic Converter 4481133. 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. This direct-fit catalytic converter is designed specifically for the 2005-2006 Audi A6 Quattro and interchanges with OE part 4F0 254 554 HX. This replacement part is designed to meet or exceed California Air Resource Board requirements, and has undergone additional testing to comply with CARB guidelines to allow for legal use in California and CARB restricted states, for the listed vehicles.