The GMC Sierra 6.2 V8 403hp (2008 - 2013) produces 403bhp and 565Nm in standard form. Our Stage 1 ECU tuning file raises output to 425bhp and 585Nm, a gain of 22bhp and 20Nm, with no hardware modifications required. The file is delivered through the ByteFLASH portal and is ready to write to the vehicle.