The Alpina B4 B4 Bi-Turbo 410hp (All) produces 410bhp and 600Nm in standard form. Our Stage 1 ECU tuning file raises output to 450bhp and 680Nm, a gain of 40bhp and 80Nm, with no hardware modifications required. The file is delivered through the ByteFLASH portal and is ready to write to the vehicle.