The Mercedes tuning specialist Brabus has just revealed its latest program for G63 AMG that attempts to make the extreme wagon even more hardcore by boosting power and adding a new set of wheels. The tuner's B63-620 performance upgrade is made up of an additional intercooler and optimized ECU software. The result is that output of AMG's meaty 5.5-liter V8 biturbo unit has increased from 544 horsepower and 561 pound-feet of torque to 620 hp and 605 lb-ft.