You can use 6x9 or 6 1/2 in the front. 6 1/2 in the rear. 6 1/2 will sound better than 6x9 if you plan on a sub. They are cleaner but have less bass.sturner06 said:Am I right having read somewhere that the front door speakers are 6x9? What about the rear doors? 6 1/2? Thinking about an upgrade to the Bose...and just making sure I am looking at the right size stuff.