The BMW 4 Series 420i 184hp (F32/33 - 2013 - 2016) produces 184bhp and 270Nm in standard form. Our Stage 1 ECU tuning file raises output to 250bhp and 440Nm, a gain of 66bhp and 170Nm, with no hardware modifications required. The file is delivered through the ByteFLASH portal and is ready to write to the vehicle.