The BMW 5 Series 523i 204hp (F10/11 - 2010 - 2016) produces 204bhp and 270Nm in standard form. Our Stage 1 ECU tuning file raises output to 265bhp and 315Nm, a gain of 61bhp and 45Nm, with no hardware modifications required. The file is delivered through the ByteFLASH portal and is ready to write to the vehicle.