Milltek Downpipes & Cat Bypass Pipes for Audi RS6 C8 4.0 V8 bi-turbo in Performance Edition (OPF/GPF Models) (2019 onwards) – Maximum Flow, Motorsport Use
This is Milltek's large-bore downpipe and de-cat for the Audi S8 D5 4.0 TFSI V8 Saloon/Sedan (OPF/GPF UK/Euro Models). It replaces the factory downpipe with a larger-bore pipe and removes the catalytic converter entirely, clearing the single most restrictive point in the exhaust for the biggest flow gain available at this position in the system. It's usually fitted alongside a Stage 2 remap, since the ECU needs to be told to expect the different readings the lambda sensors give once the cat's gone. 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 built for owners already committed to a serious power upgrade rather than a casual bolt-on, so pair it with the matching Milltek cat-back system for the full effect.
Because it removes the cat, it's intended for off-road and competition use. A de-catted car will fail an MOT emissions test and isn't legal to use on UK roads.
Specifications
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System Type: Large-bore Downpipes and Cat Bypass Pipes
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Pipe Diameter: 80mm (3.15")
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EC Approved: No
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Race System: Yes
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Fitting Time: approx. 3.5 to 4.5 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
- 80mm (3.15") pipework
- Removes the factory catalyst for maximum flow (off-road and competition use only)
- Designed, developed and manufactured in the UK by Milltek Sport
Fitment
- Audi RS6 C8 4.0 V8 bi-turbo in Performance Edition (OPF/GPF Models) (2019 onwards)
- Audi RS7 C8 4.0 V8 bi-turbo (OPF/GPF Models) (2019 onwards)
- Audi S8 D5 4.0 TFSI V8 Saloon/Sedan (OPF/GPF UK/Euro Models) (2020 onwards)
Not suitable for: the Audi RS6 C8 4.0 V8 bi-turbo in Performance Edition (Non OPF/GPF Models - USA/ROW Models), which needs the Milltek Downpipes & Cat Bypass Pipes Audi RS6 C8 4.0 V8 bi-turbo Non OPF/GPF USA ROW 20+.
Installation
Milltek quotes a fitting time of approx. 3.5 to 4.5 hours. Some versions: Fits to Milltek Sport OPF/GPF Back System include OPF/GPF Bypass - Requires Stage 2 ECU Software. Some versions: Fits to OE OPF/GPF Back System include OPF/GPF Bypass - Requires Stage 2 ECU Software. 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.
Will it fit the Audi RS7 C8 4.0 V8 bi-turbo (OPF/GPF Models)?
Yes. Milltek lists this part for the Audi RS7 C8 4.0 V8 bi-turbo (OPF/GPF Models) as well as the other models in the fitment list above.
Does it fit the Audi RS6 C8 4.0 V8 bi-turbo in Performance Edition (Non OPF/GPF Models - USA/ROW Models)?
No. For that car, choose the Milltek Downpipes & Cat Bypass Pipes Audi RS6 C8 4.0 V8 bi-turbo Non OPF/GPF USA ROW 20+.
Is it road legal?
No. Removing the catalyst 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 to Milltek Sport OPF/GPF Back System include OPF/GPF Bypass - Requires Stage 2 ECU Software". 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.
Will removing the cat cause a warning light?
Without suitable software it is likely to, as the ECU expects the readings a working catalyst gives. This is why Milltek pairs it with a remap.
How long does it take to fit?
Milltek quotes approx. 3.5 to 4.5 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.
