I recently purchased a 2011 Ford Fusion SE with 6 speaker sound setup. I originally wanted to ugrade the head unit for a touch screen, but after a little research i realized it would be pretty costly to do so while keeping steering wheel controls as well as sync. Because of this, i have moved on to the idea of upgrading the sound. My end game is great quality sound with some extra bass. (Dont need to rattle my car apart, and cant take up very much trunk space) I was wondering what everyones opinon on the best way to get this done is. (Under $700) Should i upgrade all 6 factory speakers and add an amp? sub? multichannel? If anyone could recomend a complete setup i would really appreciate it. (BTW instillation will be almost completely free). Thanks guys