N55 Signature Catted Downpipe

The Active Autowerke N55 Signature Downpipe is a high-flow, catted downpipe engineered to enhance the performance of F-Chassis N55 BMW models manufactured from September 2013 onward. It is constructed entirely from TIG-welded 304 stainless steel with a 1.5MM wall thickness, ensuring durability and longevity. The design utilizes a 3.5-inch diameter pipe with minimal bends to reduce exhaust back pressure, leading to quicker turbo spool, improved horsepower, and torque. This downpipe features a 4.5-inch GESI G-Sport Ultra High Output Catalytic Converter, which is EPA registered and OBD2 compliant for use in 49 states (not legal in California). It is designed to prevent Check Engine Lights related to catalytic efficiency and can reach operational efficiency within 9 seconds of startup. The converter is rated for applications between 500 and 850 horsepower and can withstand temperatures up to 1500 F. The 400-cell per square inch catalyst and proprietary precious metal loading technology ensure greatly reduced emissions. A key benefit of this downpipe is that NO PERFORMANCE TUNE IS NEEDED. Fitment applies to US model cars only, and compatibility with non-US models cannot be guaranteed. While the source indicates it fits all F-Chassis N55 cars from 09/2013 onward, some vendor listings suggest it may not easily fit XI (4WD) and Station Wagon variants. The downpipe is covered by a 5-year/50,000-mile warranty on shell and tube ends, and a 2-year/25,000-mile warranty on the catalytic core. However, the warranty is void if the car experiences excessive burble beyond stock, as this can physically damage the catalytic core.