The BMW M3 M3 CSL 360hp (E46 - 1998 - 2005) produces 360bhp and 370Nm in standard form. Our Stage 1 ECU tuning file raises output to 380bhp and 390Nm, a gain of 20bhp and 20Nm, with no hardware modifications required. The file is delivered through the ByteFLASH portal and is ready to write to the vehicle.