i put a sub and amp in mine after the hk one decided to blow up, you can route the cable from the battery along the inside edge back towards the bulk head where a gromet is, poke the wire through the gromet into the inner arch then back a bit further you can get back into the car by going through the same gromet as the side repeater wires then its just a case of taking the trims of a running the the cable through through to the back.