Active Autowerke BMW M3/M4 (F80/F82/F83) Equal Length Midpipe

An inline-6 engine naturally produces evenly spaced exhaust pulses, giving that smooth, full sound enthusiasts expect. But the S55's twin-turbo layout, split across unequal-length front and rear bank downpipes, disrupts that rhythm, producing a sound that comes across more like two independent inline-3s competing for attention than a proper 6-cylinder growl. Active Autowerke's Equal Length Midpipe was developed specifically to correct this at the source, a patented design (US Patent 11248511) that remains the definitive alternative to their own world-famous single midpipe.

Rather than rebuilding the rear exhaust section to equalise pipe length, which would force every owner into a completely new rear system, Active Autowerke's R&D added length specifically to the passenger-side midpipe section and engineered a new crossover using sinusoidal pipes to correct the downpipe length variance before the two sides mix. The result is a genuinely different exhaust character from the typical "S55 sound," closer to the smooth, throaty note a 6-cylinder sports car should have. This Gen 2 version introduces specially developed resonators, engineered to remove rasp and reduce the unwanted 2,000rpm buzzing some owners experience, for a noticeably smoother, deeper, and more refined tone than the original Gen 1 design it replaces. The system includes the Active Autowerke F-brace and is engineered for precise fitment.

Works with: Stock or Active Autowerke downpipes and rear exhaust systems. Fitment and sound results are only validated with these combinations, compatibility with other exhaust brands isn't guaranteed. Vehicles fitted with M Performance Exhaust (MPE) or CS exhaust should strongly consider the resonated version.

Why Choose This Equal Length Midpipe

• Patented design (US Patent 11248511) that genuinely corrects the S55's uneven exhaust pulse
• Gen 2 resonators reduce rasp and 2,000rpm buzzing versus the original Gen 1 design
• Delivers a smoother, deeper, more refined 6-cylinder tone, not the typical "S55 sound"
• Includes the Active Autowerke F-brace as standard
• Lighter than the factory system with quicker turbo spool
• Increased low-end and mid-range power from improved exhaust flow

Compatibility

• BMW F80 M3/M3 CS (S55, 2015+)
• BMW F82/F83 M4/M4 CS (S55, 2015+)

Note: if you're running catless (straight-through) downpipes, the resonated version is strongly recommended.