Milltek Sport Axle-Back Rear Silencer/Back Box Exhaust with Road Titanium Tips – BMW 1 Series M135i (F20/F21) N55 2012-2016 3/5 Door – T304 Stainless Steel Tailbox Muffler Upgrade – Direct-Fit Bolt-On Rear Section – UK Made

Unlock a richer soundtrack and a cleaner rear end for your BMW 1 Series M135i F20 F21 with this UK-crafted Milltek axle-back backbox featuring Road titanium-finish tailpipes. Built from premium T304 stainless steel and finished to an exceptional standard, this bolt-on rear section delivers a deeper tone, crisper character and everyday refinement without intrusive cabin resonance.

Key reasons to choose this Milltek backbox

• Refined, sporty note with minimal in-car resonance on motorway cruises
• High-grade T304 stainless steel throughout for long-term corrosion resistance
• Mandrel-bent pipework for smooth flow and responsive throttle feel
• Twin Road titanium-look tailpipes for a purposeful, motorsport-inspired finish
• Direct bolt-on replacement that uses factory mounts and connection points
• Precision UK engineering and hand-finished welds for consistent quality

What to expect

This axle-back section elevates the M135i’s character with a deeper growl and a more engaging tone under load while remaining civilised at steady speeds. It integrates neatly with the original centre section, retains everyday usability and enhances the rear view with premium titanium-finish tips.

Compatibility

BMW 1 Series M135i N55

• F20 5-door, 2012 onwards
• F21 3-door, 2012 onwards

Built in Britain by Milltek

Designed, developed and hand-finished in the UK, this Milltek rear section uses non-magnetic T304 stainless steel for durability and a consistent finish. The result is a high-flow, precision-fit tailbox that delivers the signature Milltek tone without the unwanted drone.

Tried, tested and loved by our community

We run Milltek systems on our own builds and our customers consistently praise the improved soundtrack, quality of the welds, and the smart titanium tailpipes that perfectly suit the M135i’s rear bumper.

Professional fitting

Want it installed properly first time? Book fitting with MJ Modifications in Warwickshire. For a quote, email info@mjmodifications.co.uk.

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