The Volkswagen Golf GTI 2.3 VR5 170hp (Mk4 - 1997 - 2003) produces 170bhp and 225Nm in standard form. Our Stage 1 ECU tuning file raises output to 185bhp and 245Nm, a gain of 15bhp and 20Nm, with no hardware modifications required. The file is delivered through the ByteFLASH portal and is ready to write to the vehicle.