I have an '06 TR, and I was going to put a new system in it. I have an alpine headunit with the fullspeed ipod hookup. I was going to go replace the 4 speakers. Anyone have an opinion on the best size to go with? In addition, I was going to get wedge box's and put 6"x9" speakers behind the rear seats by the rear windshield. I planned on adding an amp and want to know if the 6x9s need to be on a different frequency than the other speakers? Would I need a 3-channel amp for this or what? Any suggestions on ways to go with this would be appreciated!