I put 6.5" both front and rear doors on mine. IIRC they're a shallower-than-normal version? Pioneer TSG1645R. The fronts fit behind the stock grills, the rears did not.
In any case, assuming you're putting a new head unit in, get rid of (or at least bypass) the factory amp. And probably do something about the factory free-air subwoofer in back.
Edit: Again IIRC, 5 1/4" speakers will fit the rear doors if you don't want to surface-mount the aftermarket grills.
It's in the dash. Maybe behind the glove box? I used a Metra harness to plug into the factory plugs, which bypasses it.Yeah, there is something funky about the door speakers being shallower than most. I'll snag up some of the Pioneers you mentioned. Thanks for the P/N Carl! I am replacing the head unit with a double din touchscreen Sony. I need to investigate... I don't think I have a factory amp.