trying to install new amplifier; running cable from battery through firewall to the trunk; done on several cars before; looking for advice or best practices...
in addition to what ed said. if you drill through a firewall or bulkhead install a grommet or use a piece of rubber tubing [hose] to protect the wire. also make sure that where you drill,nothing is behind it. ruining your evaporator or heater core normally means that the dash will have to come out for repairs on most cars ,nothing cheap here.and pinching cable around a hinge or other movable part is begging for a fire. i see this sort of crap all the time and i wonder how these owners get up and down the road without hurting someone or themselves. take your time and don't cheap the job out, most cases another twenty minutes and 5.00 dollars of parts would have resulted in a solid installation instead of a burned out hulk.
Take your time and make yourself comfortable. Don't rush it or you will mess something up. Take everything apart first and give yourself a clear view of how and where you are going to run the pos and neg cables. Run the cables, test the connections and then re-assemble the interior panels. Make sure none of the wires are visible...
if you look under the hood, facing the cars windshield, the far right corner against the firewall, there's a dip in the sheet metal. if you drill there at the lowest point, the hole will come out behind and a little above your brake pedal. run it through there , under the side trim. not only will this seperate power from rca wires (eliminating ground noise) but it will be easy to run. if you want a professional job, take out your seats (all of em) and run it under the carpet, but i'm sure you have to remove the center console. my buddy ran the wire under the car and drilled through the floor and ran it under the rug but that is such a bad idea because if the wire corrodes from weather you will have a fire.
