The Milltek Sport Secondary Cat Back exhaust system is designed for BMW E82/E88 135i models with the N55 engine. This system is an excellent choice for the driver who wants to improve the sound quality and flow of their car without touching the primary catalytic converters.
The Secondary Cat Back system replaces the section of the exhaust system after the rear catalytic converters , retaining key components of the emissions system but freeing up the engine's soundstage and improving exhaust flow.
Rich and sporty N55 sound
Milltek has tuned this system specifically to suit the nature of the 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 during normal driving
The sound profile adds a distinctly sporty touch to the car's character while maintaining good driving comfort.
Improved flow and driving experience
Milltek Secondary Cat Back Exhaust System:
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reduces exhaust back pressure after secondary catalytic converters
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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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to work seamlessly with the standard front end
OEM-level fit ensures effortless installation and a clean finish.
304L Aircraft Grade Stainless Steel
The entire exhaust system is made of high-quality 304L grade stainless steel , which provides:
The choice of materials meets Milltek's high quality standards.
Fit
Engine: 3.0 Turbo (N55)
Model years 2010–2012