Product Specifications
3-Inch Catless Downpipe Set for BMW N63B44 4.4L Twin-Turbo
Upgrade the exhaust path on your N63B44-powered BMW with this Flashark dual catless downpipe set. Designed for the confirmed 550i, 750i xDrive, X5 xDrive50i and X6 xDrive50i applications listed below, the kit replaces both restrictive factory catalytic downpipes with larger stainless-steel piping.
The catless configuration is designed to reduce exhaust restriction after both turbochargers, support quicker turbo response and produce a deeper, more aggressive exhaust note. Each kit includes left- and right-side downpipes for the BMW twin-turbo V8 exhaust layout.
Important: BMW used several different 4.4L twin-turbo V8 engines during these model years. A 4.4L engine or matching model name alone does not confirm fitment. Verify that the vehicle has the original N63B44 engine and matches the Fitment table before ordering.
Key Features
- Complete Dual-Downpipe Set: Includes one left-side and one right-side downpipe for the N63 twin-turbo layout.
- 3-Inch Turbo-Side Inlets: Designed to create a larger exhaust path after the turbochargers.
- 2.5-Inch Outlets: Designed to connect the downpipes to the compatible downstream exhaust configuration.
- Catless Configuration: Removes the restrictive catalytic-converter section for maximum exhaust flow in permitted competition applications.
- Stainless-Steel Construction: Designed to withstand the heat and operating conditions of a twin-turbo exhaust system.
- Mandrel-Bent Tubing: Helps maintain a smoother internal exhaust path through the pipe bends.
- TIG-Welded Connections: Reinforced joints help provide strength and reliable exhaust sealing.
- Integrated Flex Sections: Help absorb normal engine and exhaust-system movement.
- Oxygen-Sensor Ports: Sensor mounting locations are incorporated into both downpipes.
What to Expect
- Reduced exhaust restriction after both turbochargers
- Potentially quicker turbo response
- Deeper and louder exhaust sound
- Improved support for compatible ECU and exhaust upgrades
Performance Notice: Actual results depend on the vehicle’s condition, ECU calibration, turbochargers, exhaust system and other modifications. A specific horsepower or torque increase is not guaranteed.
Specifications
| Product Type | Dual Catless Downpipe Set |
| Engine Application | BMW N63B44 4.4L Twin-Turbo V8 |
| Inlet Diameter | 3 Inches |
| Outlet Diameter | 2.5 Inches |
| Material | Stainless Steel |
| Construction | Mandrel-Bent and TIG-Welded |
| Catalytic Converters | Not Included / Catless |
| Installation | Professional Installation Recommended |
Package Includes
- 1 × Left-side catless downpipe
- 1 × Right-side catless downpipe
- Exhaust gaskets
- Mounting bolts and hardware shown in the product images
Installation Notes
- Professional installation is strongly recommended due to limited access around the N63 turbochargers.
- Compare all flanges, sensor locations and outlet connections before beginning installation.
- A catless exhaust setup may trigger a check-engine light or emissions-related fault codes.
- An appropriate ECU calibration may be recommended depending on the vehicle and intended application.
- Do not install or modify the parts if the connections do not match the vehicle.
Shipping, Returns & Warranty
- Shipping: Orders are normally dispatched within 1–2 business days. Delivery time depends on destination and warehouse availability.
- Returns: Covered by Flashark’s 30-day return policy when the product is new, uninstalled and in its original condition.
- Warranty: Includes a 12-month limited warranty against qualifying manufacturing defects.
Emissions Notice: This product removes the factory catalytic converters. It is not intended for use on pollution-controlled vehicles operated on public roads. Purchase and installation are subject to applicable federal, state and local emissions laws.
