The Volkswagen Golf 1.9 TDI 100hp (Mk4 - 1997 - 2003) produces 100bhp and 240Nm in standard form. Our Stage 1 ECU tuning file raises output to 140bhp and 320Nm, 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.