get a multi meter ($15) find you acc, 12v and earthfor your head unit. depending on size of amp i'd put it under passenger seat (keeps it out of your boot so it doesn't have crap put on it and away from prying eyes) run your rcas down under the center console under the carpet to your amp (preferably get a set with the remote wire in the rca's) use one of the seats mounting bolts to earth the amp (sand all paint and sound damping away first) run as short as possible pwer cable from your battery to the amp with at least one inline fuse and keep it as far from the rca's as possible. an ae82 will have 4 inch stock speaker and youu can place the tweeter in the a-piller with any hassles. If you use the originall parcel shelf buy some MDF (NOT PLASTIC) 6x9 spacers and only cut out as much as you need to. Solder everything if you can't solder at least use crimps and insulate any joins. Not That hard I'd charge maybe $120 tops would take about an hour give or take.