The Mercedes-AMG G63 is turning out to be quite popular with the aftermarket tuners. Weve seen builds from companies like Carlex Design, Wald International, Brabus, Mansory, and many others in the past. This time, another company has laid its hands on the luxurious, boxy SUV. Germany-based PerformMaster has given the G63 a twist that includes a few cosmetic changes and a power bump that pushes it over 800 horses. Is this enough to set it apart from other customized builds?