For over 30 years, Active Autowerke has set the standard for BMW performance. The Aflow High-Flow Downpipes carry that legacy forward, engineered to unlock power, cut radiant heat, and free the S63TU from the most restrictive part of its factory exhaust.
Built in-house in Miami, Florida from premium 304 stainless steel and TIG-welded throughout, each downpipe starts with a factory-matched 3.5” V-band inlet that tapers into a high-flow mandrel-bent body. The lower section that most manufacturers sell separately as a mid-pipe is included. The design retains the OEM O2 sensor heat shield, so the engine bay stays stock-looking.
A pair of 4.5” Active Aflow catalytic converters handles emissions duty with a 400 cell per square inch ultra high-flow substrate that reaches operating efficiency within 9 seconds of startup. No CEL for catalytic efficiency, and no tune required. Expect sharper throttle response, quicker spool, and a deeper tone from street to track.
Key Features
- No CEL for catalytic efficiency, guaranteed
- Active Aflow high-flow cats, EPA registered and OBD2 compliant (49 states)
- 4.5” catalytic converters with 400 cpsi ultra high-flow substrate
- Factory-matched 3.5” V-band inlet into mandrel-bent body
- Includes the lower mid-pipe section
- Faster turbo spool and improved throttle response
- 304 stainless steel with TIG-welded construction
- Direct bolt-on fit, no cutting or welding
- Retains OEM O2 sensor heat shield for a stealth look
- Rated for up to 800 HP applications
- Withstands up to 1500°F
- Reaches operating efficiency within 9 seconds of startup
- Made in Miami, Florida
- 5-Year / 50,000-Mile Warranty on shell and tube ends, 2-Year / 25,000-Mile Warranty on catalytic core
Vehicle Fitment
BMW X5M (F95) and X6M (F96), 2020 and newer
Not legal for sale or use on pollution-controlled motor vehicles registered in California per California Vehicle Code sections 27156 and 38391. Warranty on the catalytic core is void if the vehicle produces burble or overrun fueling in excess of stock, which physically destroys the catalyst.