MilltekNon-Resonated Secondary Cat BypassFitment: BMW G8X M3 M4

Overview

The Milltek Axle Back Non-Resonated Secondary Cat Bypass is engineered for BMW G8X M3 and M4 models (S58 engine). This performance component replaces the factory secondary catalyst, delivering improved exhaust flow and a sharper acoustic character. Direct fitment to OE downpipes and OE axle-back systems—no modification required.

Hand-finished T304L stainless steel construction with mandrel-bent 76.20mm (3.00") primary bore. Non-resonated design eliminates the OE resonance chamber for full-throttle note clarity. CNC-formed flanges ensure precise factory alignment and OEM hanger compatibility.

Details

• Fitment: BMW G8X M3 (G80) and M4 (G82/G83) with S58 engine
• Material: T304L stainless steel, hand-finished
• Bore: 76.20mm mandrel-bent primary
• Configuration: Non-resonated secondary cat bypass
• Install: Direct replacement—uses factory mounting points and OEM hangers
• Sound character: Aggressive full-throttle note, reduced mid-range resonance

Engineered for serious track and closed-course driving.

Fits OE system.

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

Fitment