Milltek Filter-back Exhaust for BMW 1 Series 128ti 5 Door (F40 OPF/GPF Equipped) (2021 onwards) – Sharper Sound, Filter Retained
This is Milltek's particulate filter-back system for the BMW 1 Series 128ti 5 Door (F40 OPF/GPF Equipped). It replaces everything downstream of the factory diesel or petrol particulate filter with wider-bore pipework and re-tuned silencers, cutting back pressure and sharpening the exhaust note. The filter itself is left exactly where the manufacturer fitted it, so emissions equipment is unaffected. It's offered in 9 tailpipe finishes, so you can pick the setup that suits how the car's used.
It's the right choice if you want a sportier sound and a genuine, if modest, flow improvement on a filter-equipped car, without going anywhere near the parts of the system that keep it emissions-compliant.
Specifications
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System Type: Particulate Filter-back
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Pipe Diameter: 76.2mm (3")
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EC Approved: Yes
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Race System: No
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Fitting Time: approx. 1 to 1.5 hours (Milltek figure)
Key Features
- Made from T304L aircraft-grade stainless steel, which is anti-magnetic and resists discolouration
- Mandrel-bent pipework keeps a constant diameter through every bend for unrestricted flow
- 76.2mm (3") pipework
- Fits behind the factory particulate filter, which stays in place
- Choice of 9 tailpipe finishes: GT-100 Brushed Titanium, GT-100 Burnt Titanium, GT-100 Black, GT-100 Polished, GT-115 Brushed Titanium, GT-115 Burnt Titanium, GT-115 Cerakote Black, GT-115 Polished and more
- EC approved
- Designed, developed and manufactured in the UK by Milltek Sport
Fitment
- BMW 1 Series 128ti 5 Door (F40 OPF/GPF Equipped) (2021 onwards)
Not suitable for: the BMW 1 Series M135i xDrive 5 Door (F40 OPF/GPF Equipped), which needs the Milltek Filter-back Exhaust BMW 1 Series M135i xDrive 5dr F40 OPF/GPF 19+; the BMW 1 Series M135i xDrive 5 Door (F70 OPF/GPF Equipped), which needs the Milltek Filter-back Exhaust BMW 1 Series M135i xDrive 5dr F70 OPF/GPF 24+.
Installation
Milltek quotes a fitting time of approx. 1 to 1.5 hours. Some versions: Maxton x Milltek - OPF/GPF Back System - Quad GT-100 Brushed Titanium Trims - ECE Approved - MUST BE Fitted with Maxton Diffuser. Some versions: Maxton x Milltek - OPF/GPF Back System - Quad GT-100 Burnt/Blue Titanium Trims - ECE Approved - MUST BE Fitted with Maxton Diffuser. Some versions: Maxton x Milltek - OPF/GPF Back System - Quad GT-100 Cerkote Black Trims - ECE Approved - MUST BE Fitted with Maxton Diffuser. Some versions: Maxton x Milltek - OPF/GPF Back System - Quad GT-100 Polished Trims - ECE Approved - MUST BE Fitted with Maxton Diffuser. We recommend professional fitting on a ramp. Once fitted, check the tailpipe alignment and re-check all clamps after the first few hundred miles.
Upgrade Further
Also available from Milltek for this car: Milltek GPF/OPF Bypass BMW 1 Series 128ti 5dr F40 OPF/GPF 21+.
Which tailpipe finishes are available?
You can choose from: GT-100 Brushed Titanium, GT-100 Burnt Titanium, GT-100 Black, GT-100 Polished, GT-115 Brushed Titanium, GT-115 Burnt Titanium, GT-115 Cerakote Black, GT-115 Polished, JET-115 Carbon Fibre. The finish is cosmetic and does not change the sound.
Does it fit the BMW 1 Series M135i xDrive 5 Door (F40 OPF/GPF Equipped)?
No. For that car, choose the Milltek Filter-back Exhaust BMW 1 Series M135i xDrive 5dr F40 OPF/GPF 19+.
Is it road legal?
Every version of this part is listed by Milltek as EC approved.
Do I need a remap?
No. It fits behind the factory particulate filter, so no software changes are needed.
Does it keep the factory particulate filter?
Yes. It fits behind the factory particulate filter, which stays in place.
How long does it take to fit?
Milltek quotes approx. 1 to 1.5 hours.
What is it made from?
T304L aircraft-grade stainless steel, which is anti-magnetic and resists discolouration better than lower grades.
Is there a warranty?
Yes. Milltek products are covered against defects in materials and workmanship. Contact us with your order number if you have a problem.
