The Mercedes GL 500 - 388hp (X164 - 2006 - 2012) produces 388bhp and 530Nm in standard form. Our Stage 1 ECU tuning file raises output to 405bhp and 570Nm, a gain of 17bhp and 40Nm, with no hardware modifications required. The file is delivered through the ByteFLASH portal and is ready to write to the vehicle.