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

The MAD 3.5" S58 Fat Boy is the largest BMW S58 catless downpipe on the market. Upgrade from the stock S58 downpipes for maximum airflow, power and sound — eliminating the back-pressure caused by the factory catalytic converters so your turbos spool faster and reach maximum power. As a bonus, your car sounds a whole lot meaner.

Expect up to a 30 HP increase on a tuned S58 with stock turbos — even more on upgraded turbos. The flex section reduces stress and unwanted vibration.

Features

• Largest 3.5" diameter piping versus the standard 3".
• Compatible with right- and left-hand-drive vehicles.
• Smooth bends for maximum airflow with no drone, plus a flex section.
• Up to 30 HP on stock turbos — even more with upgraded turbos.
• Lifetime warranty on defects and fitment; 90-day return; ships in 1–2 business days; spot-on fitment.

Fitment

• 2021+ BMW M3 (G80)
• 2021+ BMW M4 (G82/G83)
• 2023+ BMW M2 (G87)

SKU: MAD-047.

Emissions disclaimer: This product is not legal for sale or use on pollution-controlled vehicles operated on public roads and is intended for off-road, race, or closed-course competition use only. You are responsible for compliance with all applicable emissions laws; use 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.

Ships from our Vancouver shop — KORE SPEED is proudly Canadian-owned, with no surprise cross-border duties for Canadian buyers. Questions on fitment? Email support@korespeed.com.