Mercedes CLS63 AMG is every tuner’s favorite car, because it just has so much potential. Not just in terms of looks, but also mechanically this big Benz can be easily turned into a fire breathing monster, thanks to its 5.5 liter bi-turbo V8 engine. Check out this GAD-tuned CLS63 as a case in point.

They started out with a standard CLS63 AMG, which at 557 hp and 800 Nm of torque is fairly bonkers. The treatment includes changing the turbochargers with GAD’s own units, enhancing the cooling system, optimizing manifolds, installing a full sport exhaust system with downpipe, race catalysts and valved mufflers, and finally tweaking the software with new boost pressure and ignition timing data.

The result of all that work is, well, pretty astonishing actually. AMG’s M157 V8 now makes 803 hp and 1,150 Nm of torque, which means the CLS63 can go past 300 km/h, now that the top speed limiter has been ditched.

GAD did not make it clear if they’ve done anything to the brakes or suspension system to cope with the extra power, but then you might not be interested, because the engine treatment alone costs 25,600 Euro. A full package would have cost like 50 grand.