The BMW 1 Series M 135i 320hp (F20 - 2011 - 2015) produces 320bhp and 450Nm in standard form. Our Stage 1 ECU tuning file raises output to 385bhp and 520Nm, a gain of 65bhp and 70Nm, with no hardware modifications required. The file is delivered through the ByteFLASH portal and is ready to write to the vehicle.