The Chevrolet Express 5.3 V8 290hp (2001 - 2007) produces 290bhp and 441Nm in standard form. Our Stage 1 ECU tuning file raises output to 310bhp and 465Nm, a gain of 20bhp and 24Nm, with no hardware modifications required. The file is delivered through the ByteFLASH portal and is ready to write to the vehicle.