Check the audio section, and PLEASE run searches.... That's WAY too broad a question to ask, really. Additionally I highly recommend you not bother with rear speakers, get a nice set of fronts, amp them, and possibly a sub and be happy. There's tons of reasons for this, and feel free to ask about specifics but mostly it is because you want to hear your music coming from in front of you. factory speakers run off of deck power do a VERY good job of filling in and keeping enough sound backthere for rear seaters to hear as well without being obnoxious. One option would be to run a 4hannel amp, use 2 of those channels for your front speakers, and then bridge the other 2 to run to a modest sub sub.
Of course if you're looking for lots of boom, you'll want to go a different route.
