The Mercedes C 55 AMG 367hp (W203 - 2004 - 2007) produces 367bhp and 510Nm in standard form. Our Stage 1 ECU tuning file raises output to 385bhp and 535Nm, a gain of 18bhp and 25Nm, with no hardware modifications required. The file is delivered through the ByteFLASH portal and is ready to write to the vehicle.