B58 4.5" High-Flow Cat Downpipe

The CTS Turbo High-Flow Cat for the BMW B58 engine is engineered to maximize exhaust flow, aiming for the highest possible power gains. It replaces the factory downpipe and is designed using advanced CAD technology for a precise fit. Constructed from premium T304 stainless steel, this component features hand TIG welding and back-purging to guarantee years of reliable performance and a sporty exhaust note. Key specifications include a 4.5-inch downpipe that tapers to 3.15 inches (80mm) for seamless integration with existing exhaust systems. It is equipped with a high-flow 200-cell catalytic converter, precisely designed and tested for real-world performance upgrades. The material and construction ensure a great power increase with uncompromising performance, delivering an incredible sporty exhaust sound that remains subtle during cruising and eliminates drone with the factory exhaust. Installation requires a replacement downpipe gasket, the factory BMW gasket (part number 18328612538), which is not included. For proper operation and to avoid a check engine light, Stage 2 software is required. It also only fits cars without a GPF/OPF (Gasoline Particulate Filter/Otto Particulate Filter). The fitment spans numerous BMW models equipped with the B58 engine, including the 2016+ F20 M140i, 2016+ F22 M240i & M240i xDrive, 2016+ F30/F31/G20 340i & 340i xDrive, 2016+ F32/F33/F36/G22/G23/G26 440i & 440i xDrive, 2016+ G30/G31 540i & 540i xDrive, 2016+ G11/G12 740i & 740i xDrive, 2018+ G01 X3 M40i xDrive, 2018+ G02 X4 M40i xDrive, and 2019+ G05 X5 40i xDrive. Catalytic converters damaged by “crackle tunes” are not covered under warranty.