MAD X3 X4 M40 Catback Exhaust B58 G01 G02

The MAD Catback transforms the B58-powered X3 M40i and X4 M40i from a quiet daily into a genuinely exciting drive. It's engineered around one goal: the deepest, cleanest tone possible — rasp-free, drone-free and rattle-free — backed by freer flow and a sharper throttle.

Key features

• Deep midrange tone that adds real character without shouting.
• Rasp-free across the rev range for a crisp, clean note.
• Zero drone at cruise and zero rattle thanks to quality materials and tight construction.
• Single Y-midpipe and a central exhaust layout that optimise flow and acoustics for the cleanest possible sound.
• Dual-valve system: replaces the factory single valve so you can run a subtle daily tone (valves closed) or an aggressive bark (valves open).
• Consistent 70mm piping throughout for an even, balanced output.
• 89mm tips in Brushed Stainless, Matte Black, or Carbon Fiber.

Build & install

Made from premium 304 stainless steel. It's a direct bolt-on replacement using factory mounting points — no cutting or welding — and ships with all the clamps, bolts and gaskets you need.

Fitment

BMW X3 M40i (G01) & X4 M40i (G02), B58 turbocharged inline-six.

Shipped fast by KORE SPEED — Canadian-owned. Questions? support@korespeed.com.