The BMW 5 Series 523i 177hp (E60/61 - 2003 - 2010) produces 177bhp and 230Nm in standard form. Our Stage 1 ECU tuning file raises output to 194bhp and 250Nm, a gain of 17bhp and 20Nm, with no hardware modifications required. The file is delivered through the ByteFLASH portal and is ready to write to the vehicle.