MAD BMW B58 2025+ Gen 3 M340 M440 5" 200 Cell Catted Downpipe

Take your 2025+ BMW M340 or M440 further with the MAD B58 Gen 3 5" 200-Cell Catted Downpipe — engineered for enthusiasts who want a cleaner, more refined upgrade. Built from premium 304 stainless steel with a high-flow catalytic converter, it delivers strong power gains, more airflow and quicker turbo response, all without the fuel smell that comes with a catless design.

You get a deeper, richer, more aggressive note than stock, but smoother and cleaner than catless — the ideal balance of performance and everyday drivability for street and track. Precision welds and direct bolt-on fitment make installation hassle-free.

Features

• High-quality 304 stainless steel construction.
• 5-inch diameter for a significant airflow improvement over stock.
• High-flow catalytic converter eliminates the fuel smell common with catless downpipes.
• Deeper, aggressive yet refined exhaust note.
• Noticeable horsepower and torque increases.
• Direct bolt-on fitment for hassle-free installation.

Fitment

• 2025+ BMW M340
• 2025+ BMW M440
• 2025+ BMW X3 M50 (G45)
• 2025+ BMW X4 M50 (G46)

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.