Description
Unlock More Power, Faster Turbo Response, and an Aggressive Exhaust Note
Take your BMW or Toyota Supra equipped with the legendary B58 turbocharged engine to the next level with the MAD 4.5-Inch High-Flow Catted Downpipe. Engineered to replace the restrictive factory downpipe, this premium performance upgrade significantly improves exhaust flow, allowing your turbocharger to spool faster while increasing horsepower, torque, and throttle response.
Manufactured from high-quality T304 stainless steel, the MAD B58 Downpipe is built to withstand extreme exhaust temperatures and demanding driving conditions. Its precision mandrel-bent 4.5-inch tubing minimizes backpressure, improving engine efficiency and delivering stronger acceleration throughout the RPM range.
Equipped with a premium 200-cell high-flow catalytic converter, this downpipe offers the ideal balance between maximum performance and a deeper, more aggressive exhaust tone. The high-flow catalyst maintains excellent exhaust flow while reducing restrictions, making it an excellent upgrade for both stock and tuned B58-powered vehicles.
Designed as a true direct bolt-on replacement, the MAD B58 Catted Downpipe installs without cutting or welding and is fully compatible with both the factory exhaust system and most aftermarket cat-back exhaust systems.
Features & Benefits
- Large 4.5-inch high-flow downpipe design
- Premium T304 stainless steel construction
- High-flow 200-cell catalytic converter
- Increased horsepower and torque
- Faster turbo spool and improved throttle response
- More aggressive exhaust sound with minimal drone
- Precision mandrel-bent tubing for maximum exhaust flow
- Integrated flex section reduces vibration and stress
- Reinforced mounting bracket for added durability
- Direct bolt-on installation
- Compatible with factory and most aftermarket exhaust systems
- Fits both left-hand drive (LHD) and right-hand drive (RHD) vehicles
- No cutting, welding, or fabrication required
Performance Benefits
Replacing the restrictive factory downpipe allows your B58 engine to breathe more efficiently, providing noticeable performance improvements, including:
- Up to 30 horsepower gains on stock turbochargers
- Even greater power potential with upgraded turbo systems
- Reduced turbo lag
- Improved throttle response
- Lower exhaust backpressure
- Enhanced turbo efficiency
- Deeper, sportier exhaust tone
An ideal upgrade for daily drivers, tuned street cars, and high-performance builds.
Installation
The MAD 4.5-Inch Catted Downpipe is engineered for a simple, direct-fit installation.
- Direct replacement for the factory downpipe
- No cutting or welding required
- Compatible with OEM and aftermarket cat-back exhaust systems
- Professional installation is recommended
Important Installation Note
Downpipe gasket is not included.
Required BMW Gasket Part Number:
18328612538
Installing a new gasket is recommended to ensure a proper exhaust seal.
Warranty
- Lifetime Warranty against manufacturing defects and fitment issues
- Premium construction designed for long-lasting durability
Vehicle Fitment
Not compatible with Euro-spec B58 vehicles.
Fits the following North American B58 applications:
- 2015+ BMW M240i / M240i xDrive
- 2016–2019 BMW 340i / 340i xDrive
- 2020–2024 BMW M340i / M340i xDrive (Not compatible with 2025+ models)
- 2016+ BMW 440i / 440i xDrive
- 2016+ BMW 540i / 540i xDrive
- 2016–2020 BMW 640i Gran Turismo (G32)
- 2016+ BMW 740i / 740i xDrive
- 2017–2024 BMW X3 M40i (G01)
- 2018–2024 BMW X4 M40i (G02)
- 2019–2022 BMW X5 40i / xDrive40i (G05 Non-LCI)
- 2018–2022 BMW X6 40i / xDrive40i (G06 Non-LCI)
- 2019+ BMW X7 40i / xDrive40i (G07 Non-LCI)
- 2019+ BMW Z4 M40i (G29)
- 2019+ Toyota GR Supra 3.0 (A90/A91)
What's Included
- MAD 4.5-Inch High-Flow Catted Downpipe
- Integrated 200-cell high-flow catalytic converter
- Reinforced mounting bracket
- Integrated flex section
- Installation hardware (excluding downpipe gasket)
Emissions Disclaimer
For Off-Road and Competition Use Only
This product is not legal for sale or use on pollution-controlled vehicles operated on public roads, highways, or streets. It is intended solely for off-road, racing, or closed-course competition vehicles where emissions modifications are permitted.
By purchasing this product, you acknowledge that:
- You are responsible for complying with all applicable federal, state, and local emissions regulations.
- Use on public highways may violate the Federal Clean Air Act (42 U.S.C. §7522) and similar state laws.
- MAD and its affiliates assume no liability for improper or unlawful installation or use.
Please verify your local emissions regulations before purchasing or installing this product.
