MAD F9X S63R Fatboy Primary Downpipes – BMW M5 / M8 (F90/F92)

In Stock: Ships in 1-2 business days
Available to Order: Ships in 3-4 Weeks

Looking to unlock the full potential of your F9x?

The factory primary downpipes restrict exhaust flow and hold back the sound and performance of your twin-turbo V8.

The MAD FATBOY Catless Primary Downpipes take a different approach. Engineered to accommodate the largest possible piping diameter between the factory flanges, they maximize exhaust flow without compromising fitment.

More airflow. More power. Unrestricted performance.

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Why These Downpipes

MAD designed the FATBOY Primary Downpipes to maximize the available space between the factory flanges, creating a larger, less restrictive exhaust path for the S63R engine.

By eliminating the restrictive factory catalytic converters, these downpipes improve exhaust flow, reduce backpressure, and allow the turbos to operate more efficiently.

MAD advertises gains of up to 30 HP on stock turbos, with additional potential on upgraded turbo setups. Actual gains depend on your vehicle's configuration and tuning.

The integrated flex section helps reduce stress and unwanted vibration, while the smooth mandrel-bent construction promotes efficient exhaust flow.

Maximum airflow. Faster turbo response. Built for serious performance.

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Installation Overview

• Direct bolt-on replacement for factory primary downpipes

• Compatible with the factory exhaust system

• No cutting or welding required

• Includes necessary installation hardware and gaskets

• Professional installation recommended

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Fitment

BMW S63R Platform:

• 2018+ BMW F90 M5

• 2019+ BMW F92 M8

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Construction

• FATBOY oversized piping designed for maximum available diameter between the flanges

• Premium T304 Stainless Steel Construction

• Catless Design for Maximum Exhaust Flow

• Smooth Mandrel Bends to Minimize Turbulence

• Integrated Flex Section for Reduced Stress and Vibration

• Precision-Engineered Factory Flange Connections

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What's Included

• MAD FATBOY Catless Primary Downpipes

• Required Installation Hardware

• Gaskets

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Warranty & Returns

• Backed by MAD's limited lifetime warranty against manufacturing defects and fitment issues

• Warranty applies to the original purchaser and is subject to MAD's terms

• Products must be unused, uninstalled, and in their original condition to qualify for a standard return

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Important Notes

• Intended for off-road / motorsport use only

• Not legal for use on pollution-controlled vehicles operated on public roads

• Removing the factory catalytic converters may trigger a check engine light

• Verify emissions regulations and vehicle compatibility before purchasing

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Automaz Approved

If you're looking to maximize exhaust flow and unlock additional performance from your S63R, the MAD FATBOY Primary Downpipes deliver an oversized, unrestricted design engineered specifically for the F90 M5 and F92 M8.

With T304 stainless steel construction, integrated flex sections, and direct bolt-on fitment, these downpipes offer a purpose-built solution for high-performance applications.

More flow. More sound. More potential.

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Emissions Disclaimer

This product is not legal for sale or use on pollution-controlled vehicles operated on public roads, highways, or streets. It is intended for off-road, race, or closed-course competition use only, where such modifications are permitted.

By purchasing this product, you acknowledge and agree that:

• You are responsible for compliance with all applicable emissions laws and regulations.

• MAD, Automaz Collective, and their respective affiliates disclaim liability for improper or unlawful use of this product, to the extent permitted by law.

• Use of this part on public roads may violate the Federal Clean Air Act (42 U.S.C. § 7522) and similar state laws.