What did you retrofited to your car?

[ytt]

I was thinking to make a thread with  retrofiting made to our cars, mai be someone else want to do it.
In my 2019 V60 2019 i retrofited:
- rear parking camera
- now 360 camera
- pilot assist (just activate)
- electric front seats ( driver with memory, passanger without)
- electric folding rear headrest
- semi automatic parking
- front fog lights
- bliss and CTA
- keyless entry (with foot movement sensor for trunk)
- homelink
- adaptive headlights
- harman kardon
- illuminated sills from 90 series
- steering wheel padlle shifters
- headup display (with cutting dash)
- rear  camera washer (custom made with 10 euro )
- sport body kit from volvo accesories
-s90 armrest + knee rest for center console
- rse by key (only activation)
 - polestar software (at the dealer)
- aluminiu engine shield (from accesories)
And i think there are more, but i can't remember.
If you need info, i will answer

Wow, I'm really impressed with what you've done. I actually have a few questions for you.

How did you set up the Harman Kardon sound system and how did you figure out which parts to buy?

How did you set up the head up display system and how did you decide which parts to buy?