Not much. I hope to improve the interior storage somehow (I'm missing lots of little cubbies that my last car had), add some additional LED lights to the trunk, and add a dash cam.
I wouldn't mind changing the interior rear map lights to LEDs to match the front, but so far I haven't been able to even get the cover off to see the bulbs.
Front dome lamp cover is a little tricky. This is a thread I made when I added a switch to it.
Use the search and you'll find the rear dome in the How-To section for Gen7.
I swapped out all of the "yellow" interior lights for LEDs and what a difference! I also did the trunk. That one light is pretty decent when it's bright.
I wish it had more cubbies, too. I also wish it had a better drink holder for the driver, like by the door and not only the center console. Oh well.
I can speak well of the Viofo A129 dual dash cam and the Viofo A119 single dash cam. I used the 119 until a buddy needed one in his truck, so he got that and I went to the dual. I'm still trying to get a better location for the rear cam since I have tinted windows. But it's sure nice to have when someone comes up to your car when it's parked.