Milltek Sport Rear Silencer Back Box (Axle-Back) Exhaust for BMW M135i (F20/F21) N55 2012+ | Stainless Steel GT90 Tips | EC Approved | UK Made

BMW 1 Series M135i F20 F21 N55 Rear Section Exhaust Upgrade by Milltek

Give your N55-powered M135i the soundtrack it deserves with Milltek’s UK-manufactured rear section. This end silencer transforms the tone with a deeper, cleaner note while keeping day-to-day refinement. Built from premium T304 stainless steel with 90 mm GT90 tailpipes, it is a precision-engineered rear muffler solution for the 1 Series hot hatch that looks as good as it sounds. Road variants carry EC type approval for worry-free daily use.

Why enthusiasts choose this rear section

• T304 grade stainless throughout for long-term corrosion resistance
• Mandrel-bent tubing for smooth gas flow and consistent performance
• 3.00 inch pipework 76.20 mm for increased flow without losing mid-range punch
• Manufactured to ISO 9001 standards in the UK
• Weight saving versus factory rear box
• Crisper throttle response and a more engaging drive
• Low back pressure design for the N55 straight-six
• Twin GT90 90 mm tailpipes in a choice of finishes to suit your build

What you get

Rear silencer section only. Front and mid sections are not included. A full cat-back can be supplied separately if you want a complete system upgrade.

Vehicle compatibility

BMW M135i 1 Series F20 3-door and F21 5-door with the N55 engine, 2012 onward.

Tip options and part numbers

EC approved road options:

• SSXBM957 — GT90 polished stainless tips
• SSXBM958 — GT90 Cerakote black tips
• SSXBM1025 — GT90 titanium tips

Race sound options:

• SSXBM959 — GT90 polished stainless tips
• SSXBM960 — GT90 Cerakote black tips
• SSXBM1026 — GT90 titanium tips

Technical details

• Material: Type 304 stainless steel
• Pipe diameter: 3.00 inch 76.20 mm
• Construction: mandrel-bent, low-pressure design
• Quality: ISO 9001 manufacture, UK built

Proven on our own builds

We have fitted this rear section on customer M135i cars and our own demo vehicles. Fitment is spot on, the finish is excellent and feedback has been consistently positive. Owners love the richer exhaust tone and the premium look of the GT90 outlets.

Professional fitting

Installation available at MJ Modifications in Warwickshire. For a fitting quote or product advice, email info@mjmodifications.co.uk.

Warranty

Supplied with Milltek’s two-year warranty.

Notes

• Images are for illustration. This listing is for the rear silencer section only.
• EC approved options are available as listed above.

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