MAD B58 4.5" Catted Downpipe W/ Bracket BMW F, G Chassis & Supra

Upgrade the stock B58 downpipe to the MAD B58 4.5" Catted Downpipe for more airflow, power and sound. Crafted from premium 304 stainless steel to handle extreme heat, its smooth piping transition frees up exhaust flow for more horsepower, torque and throttle response — while 200-cell high-flow cats keep things streetable.

It bolts directly onto the stock exhaust with no cutting or welding, and works with aftermarket systems too.

Features

• 200-cell high-flow catalytic converter.
• Up to 30 HP on stock turbos — even more with upgraded turbos.
• 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

• 2015+ BMW M240i & xDrive
• 2016–2019 BMW 340i & xDrive
• 2020–2024 BMW M340i & xDrive (does not fit 2025+)
• 2016+ BMW 440i, 540i & 740i (& xDrive)
• 2017–2024 BMW X3 M40 & X4 M40 (G01/G02)
• 2019+ BMW X5 40i (G05), X7 40i (G07) & 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. Questions on fitment? Email support@korespeed.com.