This is where things get sticky. The lower runners are in place, and we install the injector rail in place. Before you install the fuel-rail bolts, the fuel-supply lines should be connected. Once the fuel rail is in place and tightened, we can install the lower runner retaining bolts. This is also the time to think about your wiring. We decided to run our FAST injector wiring down the center of the intake before we covered things up.