Swiss tuner O.CT has modified the facelifted Mercedes-AMG GT R Coupé (which was priced earlier in 2019), handing Affalterbach’s race-inspired road-car extra power and even more sinister exterior styling.

Thanks to some clever remapping of the engine control unit, the Widnau-based firm has managed to extract an additional 48 kW and 150 N.m of torque from the standard twin-turbo 4,0-litre V8 petrol mill, which is good for 430 kW and 700 N.m in stock form. Add those figures together and the tuned Mercedes-AMG GT R Coupé churns out a whopping 478 kW and 850 N.m, which is sent to the rear wheels via a seven-speed Speedshift dual-clutch transmission.

O.CT has not yet released performance figures for the tuned model. But, for reference, Mercedes-AMG says the stock GT R Coupé will reach 100 km/h from standstill in 3,6 seconds. For the record, when CAR magazine tested the pre-facelifted version in 2018, we recorded a 0-100 km/h sprint time about two-tenths slower than the German automaker's claim.

Exterior upgrades to this tuned model are purely cosmetic. But the blacked-out theme does make the car you see here look even more menacing. The most notable item is the signature Panamericana grille, found on the most powerful AMG models in Mercedes’ line-up, which has been finished in a black hue.