The Mercedes GL GL 63 AMG - 558hp (X166 - 2012 ->) produces 558bhp and 760Nm in standard form. Our Stage 1 ECU tuning file raises output to 620bhp and 900Nm, a gain of 62bhp and 140Nm, with no hardware modifications required. The file is delivered through the ByteFLASH portal and is ready to write to the vehicle.