BMW G87 M2 4" FATBOY Midpipe – Flow Is Everything

Flow is everything, and the new MAD 4" FATBOY Midpipe delivers exactly that for the BMW G87 M2.

ETA: January 14th, 2026

Designed specifically for the S58-powered G87 platform, this midpipe is built to maximize both performance and sound without compromise. Featuring a full-length single 4" center section and maintaining a minimum diameter of 3" throughout, the FATBOY Midpipe ensures optimal exhaust flow and improved throttle response.

The result is a deeper, smoother, and more aggressive tone with noticeably less rasp, even when combined with aftermarket downpipes. Whether you’re chasing performance on the track or looking for a refined yet bold sound on the street, this midpipe brings out the best in your G87 M2.

To make installation seamless, the kit also includes an upgraded brace that provides proper clearance for the larger midpipe.

Key Features:
• Full-length single 4" center section for maximum flow
• Minimum 3" diameter throughout to eliminate restrictions
• Deep, aggressive exhaust tone with reduced rasp
• Compatible with both stock and aftermarket downpipes
• Includes 3" and 2.75" reducer couplers to fit aftermarket or factory axle-back systems
• Uses the factory cut point and clamp system for an easy, reversible install
• Includes upgraded brace for proper clearance and fitment with the larger midpipe