Procedure
- This job ends with a REQUIRED retune. Injector scaling isn't optional - a car on stock scaling with bigger injectors runs pig-rich at best and unpredictably at worst.
- Depressurize the fuel system (pump fuse, crank to stall, battery off) and remove the intercooler for access.
- Unclip injector connectors, remove the fuel rail bolts, and lift the rails with injectors attached, catching the drips in rags.
- Pull each injector, fit new lubricated O-rings top and bottom, and seat the new injectors into the rail with a straight push - never a twist against a dry O-ring.
- Set the rails back on with every injector square in its bore, then torque rail bolts evenly to their small spec.
- Reconnect everything, key-on prime three times, and inspect every injector top and bottom with a flashlight before first start. Fuel on a hot boxer header is how cars burn down.
- Start, re-inspect at idle, and drive gently straight to the tune. Load the correct base map for your injector part number if your tuner supplied one.
Work at your own risk. Torque values and procedures vary by vehicle — always confirm against the factory service manual for your exact model.