The BMW Z4 2.5i 177hp (E85 - 2003 - 2008) produces 177bhp and 230Nm in standard form. Our Stage 1 ECU tuning file raises output to 193bhp and 255Nm, a gain of 16bhp and 25Nm, with no hardware modifications required. The file is delivered through the ByteFLASH portal and is ready to write to the vehicle.