MAD BMW B58 2025+ Gen 3 M340 M440 4.5" Downpipe Catless

Enhance your 2025+ BMW M340 or M440 with the MAD B58 Gen 3 Catless Downpipe. Crafted from premium 304 stainless steel, this 4.5" downpipe delivers optimal exhaust flow, durability and corrosion resistance for the best quality and longevity.

By eliminating the restrictive factory catalytic converters, it significantly boosts horsepower, sharpens throttle response and reduces turbo lag for a thrilling drive. Precision welds and exact fitment ensure a seamless, bolt-on installation with no modifications — and an aggressive, sporty exhaust note to match.

Features

• High-grade 304 stainless steel construction.
• 4.5-inch piping diameter for improved exhaust flow.
• Significant boost in horsepower and torque.
• Enhanced throttle response and reduced turbo lag.
• Aggressive, deep and sporty exhaust tone.
• Easy direct bolt-on 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.