The front doors have tweeters in the sail, in a sort of waveguide behind a wire mesh grille. The grille has black cheesecloth AND a thick foam sheet in it - I took the foam sheet out and left only the cheesecloth. The tweeters are canted enough to be on axis in the sails behind the grilles. I am using Morel MT-22 from the Hybrid Ovation set. These get two 50W channels from the DC650. The Morels snap into the BMW tabs.
The front doors also have 4" mids up high in the door. They are not standard spacing, they are using a three-bolt setup. I had steel rings made for adapters (I've used 1/4" MDF, but I wanted something stiffer). I am using Morel Hybrid Ovation 4, and I really like them. These have only 50mm of depth or so, this is a major limitation in the car. These also get 50W channels from the DC650.
This disconnect allows the door panel to be removed by a mechanic:
The car has shallow 8" enclosures underseat. These locations are the biggest compromise in the car - the speakers are under the fricking seats, but I wasn't gonna put 8" in the kicks anyway.
The woofers have the seat rail running over them and there is limited depth, but apparently BMW solved the "small vented enclosure, long vent that doesn't fit in the box" problem by building the vents into the car (B-pillar?). The only 8 that is close to dropping in is the Earthquake SWS-8. I know, it's an Earthquake - but it is the only one that comes close to fitting without SERIOUS mods. At one point I was gonna use the Rainbow WOB200, and that one needed me to hack holy hell out of the enclosure AND mod the carpet under the seat. These get 100W channels from the DC650.