Description
Upgrade your BMW or Toyota Supra with the MAD 5-Inch B58 Catted Downpipe, engineered to deliver significant improvements in horsepower, torque, throttle response, and exhaust tone while maintaining excellent reliability. Constructed from premium 304 stainless steel and featuring a high-flow 300-cell catalytic converter, this downpipe provides maximum exhaust flow without sacrificing durability.
Designed as a direct bolt-on replacement for the factory downpipe, installation requires no cutting or welding and is compatible with both factory and most aftermarket exhaust systems. The integrated flex section helps reduce stress on the exhaust system, improving long-term durability.
One of the standout features is MAD's No CEL (Check Engine Light) Guarantee. If a catalytic-converter-related check engine light occurs within the warranty period, MAD will replace the downpipe free of charge.
Whether your vehicle is stock or modified with upgraded turbochargers, this downpipe is designed to unlock additional performance while producing a deeper, more aggressive exhaust note.
Features
- Premium 304 stainless steel construction
- Large 5-inch smooth-flow design for maximum exhaust efficiency
- 300-cell high-flow catalytic converter
- No CEL Guarantee or the downpipe will be replaced free
- Direct bolt-on installation
- No cutting or welding required
- Compatible with factory and most aftermarket exhaust systems
- Flex section for improved durability
- Smooth mandrel bends for optimal airflow
- Increased horsepower, torque, and throttle response
- Gains of up to 30 horsepower on stock turbochargers with even greater potential on upgraded turbo setups
- More aggressive exhaust sound without excessive drone
- Compatible with both left-hand drive and right-hand drive vehicles
- Lifetime warranty on the downpipe
- 2-year warranty on the catalytic converter
- Ships within 1-2 business days
Warranty
- No CEL Guarantee is valid for 2 years from the original purchase date.
- Lifetime warranty covers manufacturer defects including cracks in the pipe or welds.
Installation Notes
- Direct replacement for the factory downpipe.
- Downpipe gasket is not included.
- BMW Gasket Part Number 18328612538 is required for installation.
Vehicle Fitment
Important: Does not fit European-specification B58 vehicles equipped with OPF (Otto Particulate Filter).
- 2015-Up BMW M240i
- 2015-Up BMW M240i xDrive
- 2016-2019 BMW 340i
- 2016-2019 BMW 340i xDrive
- 2020-2024 BMW M340i
- 2020-2024 BMW M340i xDrive
- Does not fit 2025 and newer BMW M340i models
- 2016-Up BMW 440i
- 2016-Up BMW 440i xDrive
- 2016-Up BMW 540i
- 2016-Up BMW 540i xDrive
- 2016-2020 BMW 640i Gran Turismo (G32)
- 2016-2020 BMW 640i xDrive Gran Turismo (G32)
- 2016-Up BMW 740i
- 2016-Up BMW 740i xDrive
- 2017-2024 BMW X3 M40i (G01)
- 2017-2024 BMW X4 M40i (G02)
- 2019-2022 BMW X5 40i (G05) Non-LCI models only
- 2019-2022 BMW X5 xDrive40i (G05) Non-LCI models only
- 2018-2022 BMW X6 40i (G06) Non-LCI models only
- 2018-2022 BMW X6 xDrive40i (G06) Non-LCI models only
- 2019-Up BMW X7 40i (G07) Non-LCI models only
- 2019-Up BMW X7 xDrive40i (G07) Non-LCI models only
- 2019-Up BMW Z4 M40i (G29)
- 2019-Up Toyota GR Supra 3.0L (A90/A91)
Important Notes
- Race use only.
- Not compatible with Euro-spec B58 vehicles equipped with OPF.
- Downpipe gasket must be purchased separately.
Emissions Disclaimer
This product is intended for off-road, racing, or closed-course competition vehicles only. It is not legal for sale or use on pollution-controlled motor vehicles operated on public roads, streets, or highways where emissions regulations apply.
By purchasing this product, you acknowledge that:
- You are responsible for ensuring compliance with all applicable federal, state, provincial, and local emissions laws.
- The manufacturer and seller assume no liability for improper or unlawful installation or use.
- Installation on pollution-controlled vehicles operated on public roads may violate the Federal Clean Air Act and similar state or local regulations.
Please verify your local emissions laws before purchasing or installing this product.
