Hello all, I'd like to start off by saying this is my first post!
I come from a 2004 Acura TL to my BO 2011 g37x and I love it infinitely more than my TL.
I digress. I have been lurking as many audio threads on here as possible and it seems nobody has asked for the speaker mounting depth in the front doors.
I'm looking to replace all the speakers and am planning on dropping a Peerless SLS 8 or 10 in the doors. The 8 is 4 inches deep and the 10 is 4.8".
Anybody have any idea how big of a baffle I could fit between the door and the door panel?
Thank you!

 

I have 6.75" CDT mids. I used a 1" spacer to fit mids with a 3" depth.
I can't remember how much depth I had but I don't think I had 4".

 

4" will be pushing it. I have CDT m6+ in the front, which have a mounting depth of 3.37". I made custom adapters to mount the woofers and offset the position downward, otherwise the surround of the woofer would be contacting part of the interior door panel. I have 3/4" MDF rings mounted to 1/4" plywood (so 1" of spacing total), and it was a very tight fit. The magnet of the woofer was touching the metal bracket inside of the door - I had to bend it inward a bit for the adapter/woofer to bolt in & sit flush in the door.

I don't think that you can use a baffle any bigger than 1" or you will run into issues with the woofer slapping against the interior door panel.