The Mercedes CLK 500 V8 - 306hp (W209 - 2003 - 2009) produces 306bhp and 460Nm in standard form. Our Stage 1 ECU tuning file raises output to 320bhp and 485Nm, a gain of 14bhp and 25Nm, with no hardware modifications required. The file is delivered through the ByteFLASH portal and is ready to write to the vehicle.