MAD BMW F & G Chassis 5" B58 Catted Downpipe M240 340 M340 440 M440 540 W/ No CEL Guarantee & Bracket

Swap your restrictive factory B58 downpipe for the MAD B58 Catted Downpipe and unlock real power, a deeper tone and dependable performance — all without tripping a check engine light. It's the upgrade for B58 owners who want more from the car with none of the headaches.

Performance

• 300-cell high-flow catalytic converter for noticeable gains and a more aggressive note, while keeping the CEL off.
• Smooth, high-flow piping that frees up exhaust flow for more horsepower, stronger torque and sharper throttle response.
• Up to 30 HP on stock turbos — even more on an upgraded setup.
• Flex section built in for long-term durability, with smooth bends that keep drone away.

Build & fit

• Premium 304 stainless steel, engineered to handle extreme heat and tough conditions.
• Direct bolt-on to the factory exhaust — no cutting or welding.
• Fully compatible with most aftermarket exhaust setups, and with right- and left-hand-drive cars.

No-CEL guarantee & warranty

• If a check engine light appears due to the catalytic converter, MAD replaces the downpipe free — valid for 2 years from purchase.
• Lifetime warranty on the downpipe against manufacturer defects such as cracks in the pipe or welds.
• 90-day return window; ships in 1–2 business days.

Fitment

• 2015+ BMW M240i & xDrive
• 2016–2019 BMW 340i & xDrive
• 2020–2024 BMW M340i & xDrive (does not fit 2025+)
• 2016+ BMW 440i & xDrive
• 2016+ BMW 540i & xDrive
• 2016+ BMW 740i & xDrive
• 2017–2024 BMW X3 M40 (G01/G02)
• 2017–2024 BMW X4 M40 (G01/G02)
• 2019+ BMW X5 40i (G05) & xDrive
• 2019+ BMW X7 40i (G07) & xDrive
• 2019+ BMW Z4 M40i (G29)
• 2019+ Toyota Supra 3.0L

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. Fitment questions? Email support@korespeed.com.