Audio Systems: nissan maxima 96, torx bolts, rear parcel shelf

Question
i want to change my speakers in both the front two doors and the back two.
what sizes and what way should i remove and replace with these speakers.
its just a regular edition, no gl or exe's

Answer
All 4 locations are 6.75 inch openings. I used to install Pioneer 6 &3/4 speakers with great results. You can also buy adapter plates and use 6.5 inch speakers.
as for removing them, you have to pull the front door panels, and the rear parcel shelf trim. Sorry, this is a big job. get a panel removal tool, and a torx set if your door handle has torx bolts.