[demick]

My 04 Box had the same Bose setup as yours. Your door speakers are not subwoofers, but are bass only (just slightly higher frequency than the subwoofer behind you). If you want to continue to use them as that, they actually sound pretty fantastic. But you will need to plan around that. That's what I did. If you try to run full frequencies through them they will sound horrible.

Dash speakers suck and you definitely need to replace those. I chose Boston Acoustics, but there are plenty of choices.

The drivers in the subwoofer enclosure were replaced by Focal's before I bought the car, so I cannot comment on the comparison there, or even what the originals sounded like.

The key to much of this is the amplifier. I used a 5 channel amp which has frequency control for each channel. I don't remember the cutoff frequencies off-hand, but the dash speakers get midrange and high, the doors get mid-bass, and the sub gets the low bass. Takes some fiddling to get happy with the frequencies and gain settings for each that satisfies your tastes.

Any good head unit with the features you want and 3 sets of preamp outputs will do fine (assuming you go with a 5 channel amp). Don't expect your FM reception to improve unless you want to figure out a way to put a standard antenna on the car.

There are lots of ways to do this depending on your tastes and goals - this was just how I did it.