Product Details
Fitment
FAQ
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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.
Fitment
Confirmed compatible applications — original BMW N63B44 4.4L twin-turbo V8 only:
| Year | Make | Model | Trim | Chassis | Engine |
|---|---|---|---|---|---|
| 2008–2014 | BMW | X6 | xDrive50i | E71 | N63B44 4.4L Twin-Turbo V8 |
| 2011–2013 | BMW | X5 | xDrive50i | E70 | N63B44 4.4L Twin-Turbo V8 |
| 2011–2013 | BMW | 550i | Base | F10 | N63B44 4.4L Twin-Turbo V8 |
| 2009–2012 | BMW | 750i | xDrive | F01 | N63B44 4.4L Twin-Turbo V8 |
Does Not Fit
- BMW X5 M or X6 M equipped with the S63 engine
- BMW X6 ActiveHybrid unless physical fitment is separately confirmed
- 2014 BMW 550i equipped with the updated N63TU engine
- 2014 BMW X5 F15 equipped with the updated N63 engine
- BMW 650i or Alpina B7 unless separately confirmed
- BMW models equipped with N63TU, N63TU2, S63 or other engine variants
- Diesel, naturally aspirated or non-4.4L models
Before ordering: Verify the model, trim, chassis and engine code. A matching 4.4L displacement alone does not confirm compatibility.
Q: Which BMW models does this downpipe set fit?
This set is designed for the confirmed original N63B44 4.4L twin-turbo V8 applications:
- 2008–2014 BMW X6 xDrive50i E71
- 2011–2013 BMW X5 xDrive50i E70
- 2011–2013 BMW 550i F10
- 2009–2012 BMW 750i xDrive F01
Confirm the vehicle’s engine code and chassis before ordering.
Q: Does this fit the BMW X5 M or X6 M?
No. The X5 M and X6 M use the BMW S63 performance engine and a different turbo-exhaust configuration. This product is designed for the confirmed original N63B44 applications only.
Q: Does it fit a 2014 BMW 550i or 2014 BMW X5?
No confirmed fitment is available for these two applications. The 2014 550i uses an updated N63 engine, and the 2014 X5 entered the F15 generation. Do not order for either application unless compatibility has been separately confirmed.
Q: Does this fit the BMW X6 ActiveHybrid?
Fitment has not been confirmed for the X6 ActiveHybrid. Its hybrid drivetrain and underbody configuration differ from the standard X6 xDrive50i. Contact Flashark with the VIN before ordering.
Q: Does this fit the BMW 650i or Alpina B7?
Not based on the currently confirmed fitment list. Some 650i and Alpina B7 models use 4.4L twin-turbo engines, but the engine family alone does not confirm downpipe compatibility. Do not order for these models unless the exact year and chassis have been separately confirmed.
Q: Is this a complete set for both turbochargers?
Yes. The package includes two catless downpipes: one for the left-side turbocharger bank and one for the right-side turbocharger bank. Gaskets and the mounting hardware shown in the product images are also included.
Q: Why are the inlet and outlet diameters different?
Each downpipe uses a 3-inch turbo-side inlet and a 2.5-inch outlet designed for the compatible downstream exhaust connection. Compare the measurements and connection style with the existing exhaust system before installation.
Q: Is this a catted or catless downpipe set?
This is a catless downpipe set. It does not contain catalytic converters and is not intended for use on pollution-controlled vehicles operated on public roads.
Q: Will these downpipes cause a check-engine light?
They may. Removing the factory catalytic converters can trigger catalyst-efficiency fault codes or a check-engine light. Results depend on the vehicle and ECU calibration. Flashark cannot guarantee that the product will prevent a warning light or pass an emissions inspection.
Q: Is an ECU tune required?
An ECU calibration is not normally required to physically install the downpipes, but an appropriate calibration may be recommended for a compatible performance build. Consult a qualified BMW tuner regarding your specific vehicle and intended use.
Q: Can I install the downpipes myself?
Professional installation is strongly recommended. Access around the N63 turbochargers is limited, and installation requires correctly removing the oxygen sensors, aligning both turbo-side connections and checking the complete system for exhaust leaks.
Q: Can the downpipes be returned after installation?
Inspect and test-fit all components before installation. Installed, modified, scratched or exhaust-exposed components may not qualify for return. Products must meet Flashark’s current return-policy conditions.
Fast Shipping Policy
Your order will be dispatched within 1-2 business days, and the package will arrive within your order's estimated date. Click for Shipping Policy
Easy Return Policy
Every order comes with a 30-day free return, provided the item is brand new, uninstalled, and in its original packaging. We cover return shipping for quality issues. Refunds are processed within 3-5 business days. Click for Return Policy
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