MAD BMW S58 3.5" Fat Boy Downpipes M2 M3 M4 G87 G80 G82 G83

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

Looking to unlock the full potential of your S58?

The factory downpipes restrict airflow and mute both power and sound — but a proper set of catless downpipes completely transforms how the car performs and feels.

The MAD 3.5” Fat Boy Catless Downpipes replace the restrictive OEM catalytic converters with the largest 3.5” piping available for the S58, engineered for maximum airflow, faster turbo spool, and increased power.

Louder.
Faster.
Unrestricted.

⸻

Why these Downpipes

By eliminating the restrictive factory catalytic converters, these downpipes allow the turbos to spool faster and operate more efficiently — resulting in noticeable gains in power and throttle response.

On a tuned setup with stock turbos, you can expect gains of up to 30HP, with even more potential on upgraded turbo setups.

The integrated flex section helps reduce stress and unwanted vibration, ensuring proper fitment and long-term reliability.

Maximum airflow.
Faster spool.
Built for real performance gains.

⸻

Installation Overview

• Direct bolt-on replacement for factory downpipes
• Compatible with OEM and aftermarket exhaust systems
• Professional installation recommended

⸻

Fitment

BMW S58 Platform:

• G80 M3
• G81 M3 Touring
• G82 M4
• G83 M4 Convertible
• G87 M2

Compatible with both left-hand drive and right-hand drive vehicles.

⸻

Construction

• 3.5” Fat Boy Diameter (Largest available for S58)
• 304 Stainless Steel Construction
• Catless Design for Maximum Flow
• Smooth Mandrel Bends
• Integrated Flex Section for Reduced Stress

⸻

What's Included

• MAD 3.5” Fat Boy Catless Downpipes
• Required Hardware

⸻

Warranty & Returns

• Eligible for a 90-day return window if unused, uninstalled, and in original condition
• Backed by a lifetime warranty on defects and fitment

⸻

Important Notes

• Intended for off-road / motorsport use only
• Not legal for use on public roads, highways, or emissions-controlled vehicles
• Does not ship to California

⸻

Automaz Approved

If you’re serious about performance on the S58 — this is where it starts.

These downpipes unlock the airflow, sound, and responsiveness that the factory setup holds back.

One of the most impactful upgrades you can make to the platform.

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 its affiliates disclaim any liability for improper or unlawful use of this product.

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

Please check your local laws before purchase and installation.