Mercedes-AMG
GT / GT S C190 · 2014 – 2021
Hold the M178 4.0 biturbo on full song — the C190 sounds savage when AMG lets it.
- Fits GT, GT S, GT C and GT R valved exhausts
- No interference with Race mode logic
- Two compact modules, one per side
- Restored to factory operation in seconds
Free UK shipping
2-year warranty
Fully reversible
The honest pitch
What this actually does to your GT / GT S
Affalterbach build incredible engines and then bury them under a polite cruise map. The C190 is no exception — Comfort is library-quiet and Sport+ only lets the flaps breathe in narrow windows.
Open Valve lets the front-mid V8 sit at the loudest setting AMG ever shipped, all the time, without any aftermarket pipework changes.
Fitment
Mercedes-AMG GT / GT S C190
Years
2014 – 2021
Install time
~10 minutes
Tools needed
None
Long read
The Mercedes-AMG GT / GT S valve story
The C190 AMG GT family — GT, GT S, GT C, GT R — wears one of the great-sounding M178 V8s and one of the more conservative AMG valve maps. Comfort is library-quiet. Sport+ opens the flaps in narrow bands; Race opens them more, but still not all of the time. The result is a front-mid V8 supercar that, on a part-throttle drive home from a track day, sounds like a slightly grumpy E-Class.
Open Valve pins both rear valve actuators open. The M178 then runs the way it does on full song at every throttle position. The cold-start lope returns at idle, the overrun crackle above 3,500 returns on every lift, and the midrange snarl past 5,000 is unmissable from inside the cabin.
Fitment on the C190 is more involved than the saloons — the actuators live deep in the rear bumper area and you do want the car on a lift to do it properly. Workshop time is about thirty minutes. Two-module kit, one per actuator.
Race mode logic — including the GT R's nine-stage traction control and the rear-wheel steering on the GT R — is untouched. We only intercept the valve actuator signal.
Install — step by step
- 01
Raise the car on a lift. Allow the exhaust to cool — the M178 silencer runs very hot.
- 02
Remove the rear lower diffuser panel (eight 10mm bolts).
- 03
Locate both valve actuator motors on the rear silencer. Disconnect each 2-pin connector.
- 04
Plug each module inline.
- 05
Mount module bodies to the chassis rail using supplied heat-rated brackets — adhesive alone is not sufficient at this temperature.
- 06
Refit diffuser panel.
- 07
Pair fob, test on idle.
In the box
- Two valve override modules (one per actuator)
- Two-button RF key fob (CR2032 pre-installed, spare in the box)
- OEM-pattern connectors — no cutting, no splicing, no scotch-locks
- Printed install card with model-specific photos and a workshop QR link
Fitment notes
- ·C190 GT, GT S, GT C, GT R (2014–2021) — all supported.
- ·Does not apply to the newer C192 (2024+) AMG GT — that car uses different actuator hardware. Separate module in development.
- ·Compatible with AMG Performance Exhaust and aftermarket valved systems retaining OEM actuators.
Mercedes-AMG GT / GT S — FAQ
Does it work across all C190 variants — GT, GT S, GT C, GT R?+
Yes. All four share the same actuator hardware and connector pinout. Same kit.
What about the AMG Performance Exhaust option?+
AMG Performance Exhaust cars use the same valve actuator type. Supported — same install.
Will it throw a warning light on the dash?+
No. The module sits in the signal path between the ECU and the actuator motor. The ECU sees a normal actuator response back, so there's nothing to flag. We've shipped thousands of these and not had a single check-engine call linked to the module itself.
Is it reversible?+
Yes, fully. Unplug the module, plug the OEM connectors back into each other, refit the trim — about three minutes' work. There's no permanent change to the car, no part cut, nothing in the ECU. Dealer service visits, MOT, sale to a new owner — pull it out and it's like it was never fitted.
Does it work with an aftermarket exhaust?+
If the aftermarket back-box retains the OEM-pattern valve actuators (most do — Akrapovic, Milltek, IPE, Capristo all run the factory motors), yes. If the system is a straight-through with no valves, there's nothing for the module to override.
Will it affect Race mode or the GT R's rear-wheel steering?+
No. Race mode logic, traction, rear-axle steer, gearbox modes and ESC stay completely unaffected. The module only touches the valve actuator signal.
Is the AMG dynamic engine mount affected?+
No. Engine mount logic reads engine RPM and torque demand directly from the ECU — unrelated to exhaust valve position.
Disclaimer
Open Valve modules are intended for off-road and motorsport use only. Please confirm your car has factory valve-actuated exhaust before ordering — if you're not sure, message us first. Professional installation recommended. Use at your own risk.
