Does your 2020 GPF equipped BMW M4 leave you lusting for a better exhaust note?

The extremely restrictive GPF/OPF/PPF is responsible for the huge reduction in tone and volume vs. the non-GPF equipped M3/M4 models.

For those who don't know what an OPF, GPF or PPF is here are some definitions:
OPF = Otto particulate filter
GPF = Gasoline particulate filter
PPF = Petrol Particulate Filter

First installed on diesels, these hugely restrictive filters catch particulates and these are then burnt off during certain drive cycles. Whilst a step forward for the environment, they are a step backwards if you are looking to improve the power, torque, boost response and sound of your M4 as they restrict flow, especially as they inevitably fill up.

The GPF is especially important to remove if you wish to tune your M4s ECU software. As the GPF is extremely restrictive, EGTs are a huge limitation in Stage 1 tuning vs. previous generation M3/M4 models without a GPF. To get the most power, torque and low EGTs, removing this is essential.

Whilst there are many exhaust systems available on the market, Milltek Sport has released a complete turbo-back GPF and cat delete exhaust system. This exhaust system is for the customer who wants the loudest M4 possible with zero emissions control and minimal silencing. This customer chose to install the complete Milltek Sport Turboback GPF delete system which includes catless downpipes, GPF delete mid-pipe, centre silencer and rear silencer with valve control and Carbon Fibre Tips.

With the complete de-restriction of the exhaust system the RSS Stage 2 ECU software is installed. This software ensures that the check engine light in relation to the GPF removal and cat removal does not illuminate as well as optimising ignition, fuelling, boost, VANOS and many other maps inside the ECU for improved power, torque and driveability!

To help the engine breathe a little better the Eventuri Panel Filters are installed which replace the restrictive paper elements.

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