The BMW S58 is already one of BMW M’s most capable modern performance engines, combining twin-turbocharging, strong factory internals, and substantial tuning potential. For owners of the BMW F97 X3M and F98 X4M, improving the exhaust side of the engine can be an important part of building a more responsive and performance-focused setup.

The MAD BMW S58 X3M X4M Catted High Flow 200 Cell Downpipes are designed to reduce exhaust restriction while retaining high-flow catalytic converters. Using 304 stainless steel construction, smooth mandrel-bent piping, integrated flex sections, and 200-cell high-flow race catalytic converters, the MAD-161 downpipes provide a freer-flowing alternative to the factory downpipes.

The result is a performance-oriented exhaust upgrade intended to support increased horsepower and torque potential, sharper throttle response, and a deeper, more aggressive exhaust character while maintaining a catted configuration.

Designed Specifically for the BMW S58 X3M and X4M

The MAD-161 downpipes are developed specifically for the F97 BMW X3M and F98 BMW X4M, both powered by BMW’s S58 twin-turbocharged inline-six.

These vehicles combine the performance hardware of BMW M with the practicality of an SUV and Sport Activity Coupe platform. As power levels increase through tuning and supporting modifications, exhaust flow becomes increasingly important. The factory exhaust system must balance emissions requirements, noise regulations, durability, and everyday drivability, while performance builds often require greater flow capacity.

MAD addresses this with a high-flow downpipe design intended to reduce restriction immediately downstream of the S58 turbochargers.

The result is a component suited to owners building a more performance-oriented X3M or X4M without moving to a completely catless downpipe configuration.

200-Cell High-Flow Catalytic Converters

One of the defining features of the MAD-161 is its 200-cell high-flow catalytic converter configuration.

Compared with more restrictive factory catalytic converter designs, a high-flow 200-cell catalyst is intended to provide a more open exhaust path while retaining catalytic converter elements within the downpipe assembly.

This makes the MAD downpipes a different approach from completely catless systems. The 200-cell race catalysts are designed around high exhaust flow and performance applications, helping reduce restriction while contributing to the more aggressive exhaust character expected from a performance downpipe.

For S58 owners looking to modify exhaust flow, the catalytic converter configuration is an important part of the overall design.

304 Stainless Steel Construction

MAD constructs the S58 downpipes from 304 stainless steel, a material commonly used for performance exhaust components because of its durability and resistance to corrosion and high-temperature operating conditions.

Downpipes operate in one of the most demanding areas of an exhaust system. They are positioned close to the turbochargers and are exposed to substantial exhaust temperatures, thermal cycling, vibration, and pressure.

The 304 stainless steel construction of the MAD-161 is designed to withstand these conditions while providing a durable foundation for a long-term performance build.

Smooth Mandrel-Bent Piping

The MAD-161 uses smooth mandrel-bent piping to maintain a consistent internal path through the downpipe assembly.

Mandrel bending helps minimize deformation through bends, allowing the tubing to maintain its intended diameter instead of creating unnecessary restrictions through sharply compressed sections.

For a turbocharged engine such as the S58, maintaining efficient exhaust flow is important because the exhaust side of the turbocharger directly influences how effectively exhaust energy can be used to drive the turbine.

By combining smooth bends with the high-flow catalyst design, MAD aims to create a freer-flowing path from the turbochargers into the rest of the exhaust system.

Potential Gains of Up to 30 Horsepower

According to MAD, the S58 downpipes can provide potential gains of up to 30 horsepower on stock turbochargers, depending on the vehicle configuration and supporting setup.

Actual results can vary based on factors such as ECU calibration, fuel quality, environmental conditions, vehicle condition, and other modifications.

The performance potential can also extend further when the downpipes are used as part of a more extensively modified S58 setup with upgraded turbochargers and supporting modifications.

Rather than functioning as an isolated power modification, high-flow downpipes can become part of a larger performance system that includes engine calibration, intake improvements, intercooling, turbocharger upgrades, and other supporting hardware.

Improved Exhaust Flow and Throttle Response

Reducing exhaust restriction can provide benefits beyond peak horsepower.

The MAD-161 downpipes are designed to improve exhaust flow through the S58, which can contribute to a more responsive power delivery and improved throttle response.

On a turbocharged engine, exhaust flow plays a direct role in turbocharger operation. A less restrictive path can help the turbochargers move exhaust gases more efficiently, supporting the engine's ability to produce power as airflow and boost increase.

The exact effect will depend on the vehicle's calibration and configuration, but the downpipes provide additional exhaust-flow capacity for both stock-turbo and upgraded-turbo S58 builds.

A More Aggressive S58 Exhaust Note

The S58's exhaust character is an important part of the driving experience, particularly on the X3M and X4M Competition.

The MAD high-flow downpipes are designed not only for performance but also to alter the character of the exhaust system. Their freer-flowing construction can produce a deeper and more aggressive exhaust note compared with the factory configuration.

At the same time, MAD specifically designed the piping to improve airflow without excessive drone, making the system suitable for performance-focused builds where exhaust sound is an important consideration.

The final sound level and character will naturally depend on the rest of the exhaust system. The MAD downpipes can be used with the factory exhaust system as well as most aftermarket exhaust systems, giving owners flexibility when planning additional exhaust upgrades.

Integrated Flex Sections for Durability

The MAD-161 incorporates integrated flex sections into the downpipe design.

Flex sections help accommodate movement and vibration within the exhaust system while reducing stress transferred to surrounding components. This is particularly important in a turbocharged performance application where the exhaust system is exposed to significant heat and mechanical movement.

Combined with the 304 stainless steel construction, the integrated flex sections contribute to the durability-focused design of the downpipes.

Direct Bolt-On Installation

The MAD S58 downpipes are designed for direct bolt-on installation.

The installation does not require cutting or welding, allowing the downpipes to connect to the vehicle's existing exhaust configuration using the intended mounting points and connections.

This also gives owners greater flexibility when modifying the rest of the exhaust system later. The MAD-161 is designed to work with the factory exhaust system and most aftermarket exhaust systems, making it suitable for both relatively simple upgrades and more extensively modified X3M and X4M builds.

As with any downpipe installation, professional installation is recommended to ensure correct fitment, hardware torque, exhaust alignment, and proper sealing.

Compatible With RHD and LHD Vehicles

The MAD-161 is designed for compatibility with both left-hand-drive (LHD) and right-hand-drive (RHD) vehicles.

This makes the downpipes suitable for S58-powered F97 X3M and F98 X4M applications across different markets, provided the vehicle falls within the specified fitment range.

Before ordering, always verify the exact model, model year, chassis, and vehicle configuration to ensure compatibility.

No Check Engine Light Guarantee

MAD also includes a No Check Engine Light Guarantee with these downpipes.

Because the downpipes incorporate high-flow catalytic converters rather than being completely catless, the design is intended to maintain a catted configuration while improving exhaust flow.

However, emissions-related behavior can depend on vehicle calibration, software, operating conditions, and applicable vehicle configuration. Owners should always verify compatibility with their specific vehicle and intended use.

Lifetime Warranty

The MAD S58 downpipes are backed by a lifetime warranty against manufacturing defects and fitment issues.

This provides additional coverage for the hardware itself and reflects the manufacturer's focus on durability and proper vehicle fitment.

Warranty terms and conditions should always be reviewed before installation.

An Upgrade for Stock-Turbo and Modified S58 Builds

The MAD-161 downpipes can serve as part of different levels of S58 modification.

On a vehicle retaining the factory turbochargers, the high-flow downpipes provide a freer-flowing exhaust path and potential power gains of up to 30 horsepower according to MAD.

For vehicles using upgraded turbochargers, the downpipes can become an important supporting component as the engine's airflow and power demands increase. Additional supporting modifications and an appropriate ECU calibration may be required depending on the desired power level and hardware configuration.

This makes the MAD-161 suitable for owners who want to establish a stronger exhaust-flow foundation before progressing to additional S58 upgrades.

BMW F97 X3M and F98 X4M Fitment

The MAD-161 downpipes are designed for the following BMW S58-powered applications:

• 2020+ BMW X3M (F97)
• 2020+ BMW X3M Competition (F97)
• 2020+ BMW X4M (F98)
• 2020+ BMW X4M Competition (F98)

Always verify your vehicle's exact model year, chassis, engine, and configuration before ordering.

Race Use Only – Emissions Disclaimer

The MAD BMW S58 200-Cell Race Catted Downpipes are intended for off-road, racing, or closed-course competition use where permitted.

This product is not legal for sale or use on pollution-controlled vehicles operated on public roads, highways, or streets where prohibited by applicable emissions laws.

By purchasing or installing this product, the vehicle owner is responsible for determining and complying with all applicable federal, state, and local emissions regulations. Use on public roads may violate the Federal Clean Air Act (42 U.S.C. § 7522) and applicable state laws.

Customers should review all applicable regulations before purchasing or installing the product.

MAD-161: High-Flow S58 Downpipes for the X3M and X4M

For owners building a performance-focused BMW F97 X3M or F98 X4M, the MAD S58 200-Cell High-Flow Catted Downpipes provide a direct-fit exhaust-flow upgrade centered around the S58's turbocharged architecture.

With 200-cell high-flow race catalytic converters, 304 stainless steel construction, smooth mandrel-bent piping, integrated flex sections, direct bolt-on fitment, and compatibility with both factory and most aftermarket exhaust systems, the MAD-161 is designed to support increased exhaust flow and the performance potential of modified S58 platforms.

With potential gains of up to 30 horsepower on stock turbochargers, additional potential with upgraded turbochargers, and a deeper, more aggressive exhaust character, the MAD-161 provides a performance-oriented foundation for F97 X3M and F98 X4M builds.

Key Features

• 200-cell high-flow race catalytic converters
• 304 stainless steel construction
• Smooth mandrel-bent piping
• Integrated flex sections
• Designed to maximize exhaust airflow
• Potential gains of up to 30 HP on stock turbochargers
• Additional performance potential with upgraded turbochargers
• More aggressive exhaust tone
• Designed to avoid excessive drone
• Compatible with LHD and RHD vehicles
• Direct bolt-on installation
• No cutting or welding required
• Compatible with factory exhaust systems
• Compatible with most aftermarket exhaust systems
• No Check Engine Light Guarantee
• Lifetime warranty against manufacturing defects and fitment issues
• Designed for BMW F97 X3M and F98 X4M

Product Link: https://x-ph.com/mad-bmw-s58-x3m-x4m-catted-high-flow-200-cell-downpipes-mad-161/