always thought simpler was best with ice, nice set of components up front and then just bass from the rear. The best car I ever sat in had only 5 speakers, 2 in each door (5 1/4" components with tweeters) and a 10" sub in the back. Speakers in the rear other than bass just fucks around with the sound stage, you dont go to a concert and turn your back on the speakers, you expect sound to come towards your front which is what you should try create in the car. Bass speakers can be put anywhere as you feel bass more than hear it. Just my 2p worth.