I have been into all locations, but the subwoofer. It is very weak. I faded to the LR and had the LR speaker unhooked and sub made very little noise.
Front speakers are 3.5". I put JBL due to liking the sound and them being 2 ohm. About anything will fit though. Depth wasn't an issue.
Front door speakers are 6x9". They are not full range though. Only make mids down to midbass sound. I tried new JBL 6x9 there and they didn't sound any better due to the limited frequencies playing through them. I left them alone as upgraded speakers will do very little. Almost identical setup to my Grand Cherokee. Tons of research and nothing to upgrade front doors to without rewiring and another amp/head unit.
Rear doors are 6x9", but are full range. I put the new JBL here and they sounded great.
I got the factory wiring diagrams out of Alldata. PSA-All speaker polarities didn't match how the speakers tested. I tested each speaker with a battery and the positive on the speaker corresponded to the negative on the wiring diagram in all locations. I am ASE certified and a college level Automotive Technology instructor. I have never run into this before. I installed all speakers on how they tested and system sounds great. The rear door adapter polarities had to be swapped. The fronts, however, were correct.
Biggest bang for the buck is to replace the front 3.5" speakers. That really cleared up the muddy sound. The 6x9 in the rear really rounded it out. JBL speakers take a while to break in, but I'm impressed with how they sound. Once broken in, I'll see if I need to put my powered sub under the seat. It is just sitting on the shelf, so may need to throw it in for fun.
