Milltek GPF/OPF Bypass for BMW 1 Series 128ti 5 Door (F40 OPF/GPF Equipped) (2021 onwards) – Filter Delete, Motorsport Use
This is Milltek's GPF/OPF bypass pipe for the BMW 1 Series 128ti 5 Door (F40 OPF/GPF Equipped). It replaces the section of pipe housing the factory petrol particulate filter with a straight-through pipe, clearing the last major restriction left in a modern turbocharged petrol exhaust once a de-cat and remap are already in place. It's offered in versions to suit the factory or a Milltek system, so you can pick the setup that suits how the car's used.
It's aimed at owners already running a de-cat and a supporting remap who want to clear the final restriction in the system, not a bolt-on for a car that needs to stay road legal.
Because it removes the particulate filter, it's intended for off-road and competition use. A car with the GPF/OPF removed will fail an MOT emissions test and isn't legal to use on UK roads.
Specifications
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System Type: GPF/OPF Bypass
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Pipe Diameter: 76.2mm (3")
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EC Approved: No
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Race System: Yes
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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
- Straight-through pipe in place of the factory petrol particulate filter (off-road and competition use only)
- 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 (F70 OPF/GPF Equipped), which needs the Milltek GPF/OPF Bypass 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: Fits to the Milltek Sport OPF/GPF Back System Only - Requires Stage 2 ECU Remap or OPF/GPF Bypass Module (Available from www.leib-engineering.de). Some versions: Fits to the OE OPF/GPF Back System Only MSBM393 - Requires Stage 2 ECU Remap or OPF/GPF Bypass Module (Available from www.leib-engineering.de). This work involves removing parts close to the turbo and engine, so we recommend fitting by a specialist with a ramp and suitable software support.
Upgrade Further
Also available from Milltek for this car: Milltek Filter-back Exhaust BMW 1 Series 128ti 5dr F40 OPF/GPF 21+.
Does it fit the BMW 1 Series M135i xDrive 5 Door (F70 OPF/GPF Equipped)?
No. For that car, choose the Milltek GPF/OPF Bypass BMW 1 Series M135i xDrive 5dr F70 OPF/GPF 24+.
Is it road legal?
No. Removing the particulate filter means the car will fail an MOT emissions test, so it is for off-road and competition use only.
Do I need a remap?
Yes. Milltek notes: "Fits Milltek Cat Back Only, Stage 2 Remap Required". Without suitable software the engine management is likely to log faults.
Can I use it with my standard exhaust?
It depends on the version. Some are made for the factory (OE) system and others for the Milltek cat-back, so check the notes for the option you choose.
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.
