How many wires do you need to run through the firewall, light gauge wire, amp power ect? If its just something like 4mm auto wire you can draw them through the rubber grommet with the main wiring harness on the drivers side. If its something thicker like an amp power wire you can either drill a new hole somewhere and put a rubber grommet in it or you can also run it back through with the bonnet release cable if you enlarge the hole in the existing grommet a little bit.