I’m looking to replace my stock Bose with a bespoke stereo using mostly components I have already (all except a double DIN). I have a cheaper 3-way component stereo (Focal Access 165 A3) and a more expensive 2-way component (Focal Polyglass 165) that I know I can fit in the doors fairly easily, the tweeters in the existing location and the rest where the existing woofers are, using a bespoke fibreglass enclosure for the 3-way. I already have an 8” Focal sub in a bespoke plywood enclosure replacing the ski hatch powered by a 500w mono amp.

As the the amp is powerful (4x100w RMS or 2x200w RMS if I use the new double DIN’s output for the rear speakers) I’m tempted to splash out and buy some larger 3-way speakers such as the Morel Elate where there might not be room for the larger mids and woofers together.

To save me ripping off a door panel to look at possible locations for the mids elsewhere, does anyone have any advice for the best locations?

 

I would stick with the 2 way component. It would be hard to mount another speaker anywhere else in the door. Although You could utilize the center channel speaker in the dash for one as you can fit a 3-4” speaker

 

I have Boston Acoustic 3 way components on my doors. A custom cardboard mount was made to fit the bass and midrange speakers on the door where the factory speaker was.

 

Way back I also used Focal Polyglass 165 components in the doors and 2-way Access speakers in the back: https://www.rx8club.com/series-i-int...-stereo-19899/
Still going strong after so many years. I have a proper amp to drive the speakers and a sub since then of course.
The 8" sub in the passthrough may not be the best, it probably won't go deep enough. I used to have the same setup, but then replaced it with a 10" sub in a fiberglass enclosure in the trunk corner. Much better that way.
However, this will also depend on the box for the sub, so it may work out...