Performance tuner Posaidon has unveiled a power kit for the range-topping Mercedes-Benz GLS 63 4MATIC (X166). The previous generation of the luxury SUV ships with a 5.5-liter twin-turbo V8 engine known as the M 157. In its stock form, the unit produces 585 hp along with 700 Nm of torque. Posaidon adds an in-house designed turbocharger, reworks intake and exhaust systems from the ground up, and tinkers with the ECU to deliver a spectacular boost to 853 hp and 1,300 Nm of torque.

Furthermore, the tuner says it had to put a hard limit at the maximum torque. Apparently, the team did all it could to reinforce the stock AMG Speedshift Plus 7G-Tronic transmission, but exceeding 1,300 Nm could still cause it to self-destruct.


To help you harness that kind of power, the company ships the upgrade with carbon-ceramic brakes it sources from the S-Class (W222). The front axle gets 420-millimeter (16.4-inch) brake discs and 6-piston calipers, while the rear one makes do with 360-mm (14-inch) ones.

The exterior of Posaidon’s Mercedes-Benz GLS 63 4MATIC fits the ‘grey horse’ description perfectly. There are a couple carbon trim elements, the radiator grille looks taken from a Mercedes-AMG GLE Coupe (C292), and the multimedia system is new – but that is about all.