Ok. That's a bit of a teaser because my mods thus far are pretty tame. 2 days in and I've swapped the cheap (4) ceiling 5.25" speakers for (4) kicker 6.5" speakers. Slightly larger but just screwed in and looks great. I had planned to paint the grills white with a rattle can but my family actually prefers the black. Very easy to do and made a big difference in the sound. Now I'm considering adding a small sub under the passenger dash. We will see.
Mod #2. The TV in the bedroom was mounted completely vertical which causes the viewing angle while laying in the bed to have a very dark picture. So I bought (2) 4mm x .7 20mm screws. I took the tv off the bracket and replaced the top two screws with the above and added (8) #8 flat washers. This tilted the TV forward and significantly improved the picture. I probably could have used (10). Much better and I'm surprised they shipped them without having done something similar. Cost about $1.50.