The Mercedes S 500 Turbo 435hp (W221 - 2005 - 2013) produces 435bhp and 700Nm in standard form. Our Stage 1 ECU tuning file raises output to 510bhp and 820Nm, a gain of 75bhp and 120Nm, with no hardware modifications required. The file is delivered through the ByteFLASH portal and is ready to write to the vehicle.