Ta da!
The fronts are 6.5" woofers. A component set should go in OK with ample space behind the door card for most passive cross over systems that come with the speakers.
It depends how much you want to spend. On the list I would have JL Audio, Rainbow and Hertz for a high end system. Infinity speakers will be an upgrade but IMO there are better for the money. Focal are nice, but the tweeter is quite bright and in the Zed the tweeter locations are quite close to you - you might find them a bit harsh.
Depending what headunit you are linking them up to, this can be dialled out and a good sound obtained. Anything using the existing BOSE or other standard set-up will not be making the most out of the speakers at all. If you have the time, I would spend some money on some Dynamat Xtreme to sound proof the doors. Spending time doing that will hugely increase the quality of sound from the speakers.