Xoutpost.com - Advise on Sound System Build

I just picked up a 4.8is a couple of weeks ago and as soon as I sell my M5 I plan on doing a complete sound system upgrade. It is DSP but is the Non Nav unit. I know it had an aftermarket system in it before, because I can already tell some speakers are missing, the sub box isn't there, the CD changer is not mounted, but the good news all the speakers wires are labeled. lol.:bustingup

Anyways, I have some components left over from my old M3. I already have a set of Boston Acoustic Pro 6.5 components, an Alpine PDX V9-5, and a JL 8W7. I plan on picking up a new Dynavin, had one in my M3, and looks like the new one is much better with 4V pre out, EQ, and time alignment.

Tweeter Placement: I plan on mounting the Boston Pro up front, and was curious if you had better results mounting the tweeters in the dash or the stock location by the mirrors? I could also mount them in the door with the midrange just like a 2 way speaker.

Rear Fill: I would like to have some rear fill, but don't want to screw my sound stage up. In my M3 of course I didn't use rear speakers, and I had all 400W (Alpine PDX V9 is 100x4, 500x1) going to the Boston Pro's and they sounded great. So I can either run the rears off the amp, but I'm thinking of just running them off of the radio and have them turned down when there is no one in the back. But the Dynavin does have time alignment so not sure how it would work. I would also like to just have midbass and midrange in the rear, anyone have suggestions on what speakers to buy?

Sub: As I said I already have a JL 8W7 which is a great sub, but I would like to build a box so that it is stealth (zero cheif's design) but unfortunately there is no way the W7 will fit back there. :( I know most of you use the shallow pioneer but was curious on what better options there might be. I see that Sundown has a couple of shallow mount subs (SD-2's), which I hear nothing but good things about. The 8" can be in as small as .25 to .5 cubic feet. The 10" needs .5 cubic feet, but both have the same mounting depth 4.5". Not sure which would work best (seems like the internal volume is around .45 cubic feet?). Anyone know how much mounting depth there is to work with this box? Other subs I am looking at was the Kicker L7 or the JL Audio 10TW3.