GESI Catted Downpipe for BMW B58

The Active Autowerke BMW G2X G4X B58 M340i M440i GESI Catted Downpipe is engineered to significantly reduce exhaust back pressure, allowing the B58 engine's turbocharger to spool more quickly and efficiently. By replacing the restrictive factory downpipe with 4.5-inch diameter, 304 stainless steel piping, this component facilitates faster evacuation of spent exhaust gases. This not only enhances turbo response but also contributes to increased horsepower and torque output, making it ideal for forced induction applications. This downpipe features a high-flow GESI G-Sport Ultra High Output Catalytic Converter, constructed from 304 stainless steel. The converter is EPA registered and fully OBD2 compliant, designed to prevent common 'Check Engine Lights' on 1996 and newer vehicles, and is rated for engines producing between 500 and 850 horsepower. While emissions meet EPA standards, these catalytic converters are not legal for use in California. The construction includes 1.5mm thick walls and is TIG welded for durability, with a cast upper stainless steel V-band for precise fitment. Key specifications include 4.50-inch diameter piping, a 400-cell per square inch catalyst density, and a temperature rating of 1500°F. The downpipe is covered by a 5-year/50,000-mile warranty on the shell and tube ends, and a 2-year/25,000-mile warranty on the catalytic core. It is noted that excessive burble beyond stock levels will void the warranty. Fitment is primarily for US model cars, and compatibility with non-US models cannot be guaranteed. This downpipe is designed for the Gen 2 B58 TU1 engine and does not fit the Gen 3 B58 TU2 found in many 2025+ BMW models.