My car has hifi audio as standard, as a result with cic upgrade, i have ampless low output from my cic, hence the front are feedbacked to my Pioneer odr 2's Aux in, the rear are feedback into a 2 ch amp, so it can power the 2 rear speaker (for parktronic only, lol) , feeding the low output directly to the speakers will kill the cic output in long run. so don't do that!.
For the door panels, the window switch socket works, you just need to cut and extend the wires cause the switch is now in a different location.
You also need new led modules , for the door handle light and night view light , which i cut the original led wires and hooked it up.
I bought the door panels with grey leather, hence they are re leathered to black as well.
In my case, my audio setup is a professional audio setup that m-individual audio would not come near too

They are flux reference speaker hooked to sinfoni and powered by pioneer odr's 30band individual l/r eq
the door is custom cut, custom molded and the 6.5" is fitted there, my pillars are custom fitted with a 3.5" mid and 1.7inch tweeter too.