MAD BMW S55 3.5" Fat Boy Downpipes M2C M3 M4 W/ Flex Section

Say hello to the largest S55 downpipes on the market: the MAD S55 Fat Boy 3.5" Catless Downpipes. Swapping the restrictive stock cats for full 3.5" piping eliminates backpressure so the turbos spool faster and make maximum power — with a much meaner exhaust note. The flex section reduces stress and vibration from heat and engine movement.

Expect up to a 30 HP increase on a tuned S55 with stock turbos, and even more on upgraded turbos.

Features

• Largest-diameter 3.5" catless design for maximum flow.
• Compatible with right- and left-hand-drive vehicles.
• Smooth bends for maximum airflow with no drone, plus a flex section.
• Lifetime warranty on defects and fitment; 90-day return; ships in 1–2 business days; spot-on fitment.

Fitment

• 2018+ BMW M2 Competition
• 2014+ BMW M3
• 2015+ BMW M4

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.