I currently have my system in progress. I will be using a Pioneer P99RS for head unit that will handle all eq / crossover / time alignment. I am running ID ultra's on minihorns with B&C high sensitivity mids in doors (5 1/4" in stock location). I'm going to try to squeeze 2 - JL 13tw5 in the...
You'll need a set of 4x10 to 6x9 adapters. Spend the couple extra bucks and get the speaker plugs too. This way you can just plug into the factory wires without cutting anything. As far as speakers, just get a decent brand (Pioneer, Kenwood, etc) cheaper sets are not worth the work to put...