The Milltek Sport Cat Back Exhaust System is designed for BMW M135i drivers who want to improve the sound, flow and overall driving experience of their car while maintaining the original drivability. While the factory system restricts sound and exhaust flow, Milltek's Cat Back solution unleashes the character of the N55 engine in a controlled and high-quality way.
The Cat Back system replaces the section of the exhaust system after the catalytic converter and brings with it a clearly sportier and richer sound.
Sporty and balanced N55 sound profile
Milltek has tuned this system specifically for the M135i's 3.0-liter N55 engine:
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Deeper and fuller sound at idle
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Clearer and more powerful sound during acceleration
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Sporty yet controlled sound at high revs
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No annoying resonance or drone at cruising speeds
The sound profile emphasizes the engine's character without compromising daily driving comfort.
Improved flow and ride feel
Milltek Cat Back Exhaust System:
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reduces exhaust back pressure
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supports engine's sensitive throttle response
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improves the overall driving experience
The freer-flowing structure also supports moderate power upgrades.
Easy bolt-on installation
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to fit directly into the car's original mounting points
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for installation without welding or permanent changes
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compatible with rear-wheel drive (not xDrive) models
OEM-level fit ensures effortless installation and a clean finish.
304L Aircraft Grade Stainless Steel
The entire system is made of high-quality 304L grade stainless steel , which offers:
The choice of materials meets Milltek's high quality standards.
Fit
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BMW M135i 3-door (F20)
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BMW M135i 5-door (F21)
Engine: 3.0 Turbo (N55)
Rear-wheel drive
No xDrive
Model years 2012–2016