Keep the check engine light off with MagnaFlow OEM Grade Federal/EPA Compliant Direct-Fit Manifold Catalytic Converter 51138. With features including free-flowing mandrel-bent tubing and highly corrosion resistant stainless steel construction, easily install this 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 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 Manifold Catalytic Converter is designed to fit the 2007-2011 Audi A6 Quattro 4.2L & 2007-2008 Audi A8 Quattro 4.2L. MagnaFlow 51138 includes (4) Nuts, (3) Bolts, (2) Flange Gaskets and interchanges with OE parts 079 253 019 EX, 079 253 019 FX, 079 253 019 HX. 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 California or Federal/EPA Emission systems.