MilltekResonated Secondary Cat BypassFitment: BMW G8X M3 M4

Overview

Milltek Axle Back Resonated Secondary Cat Bypass for BMW G8X M3 and M4. Direct fitment to OE downpipes and OE axle-back systems. Hand-finished T304L stainless steel construction with 3.00" (76.20mm) mandrel-bent piping engineered to optimize exhaust flow while preserving factory integration points.

This resonated design eliminates secondary catalyst restriction while maintaining acoustic balance through OE resonance point engineering. Uses factory hangers and mounting locations—no modification required. T304L material resists thermal cycling corrosion common in secondary cat applications.

Details

Fitment Notes & Installation

• BMW M3 G80 (2021+) and BMW M4 G82/G83 (2021+)
• Fits OE downpipes only
• Fits OE axle-back systems only
• Direct factory fitment—no welding, cutting, or modification
• OEM hanger and sensor compatibility

Milltek secondary cat bypasses are engineered alternatives to full cat-back systems for buyers seeking midpipe performance gains without replacing the entire system.

Fits OE system.

Designed and manufactured in the UK with 40+ years of performance exhaust heritage. Tested at the Nurburgring.

Fitment