The Mercedes S 63 AMG 525hp (W221 - 2005 - 2013) produces 525bhp and 630Nm in standard form. Our Stage 1 ECU tuning file raises output to 541bhp and 650Nm, a gain of 16bhp and 20Nm, with no hardware modifications required. The file is delivered through the ByteFLASH portal and is ready to write to the vehicle.