I used a car specific install kit from Connects2 to fit the HU. The slightly larger than normal surround comes from the kit and the cage they supply had adjustable side plates so the depth in the dash that the HU sits at can be adjusted to give a flush finish.
I've taken the 'A' pillar trim off before to fit the alarm sensors so it was simple enough to do the same again. There is wiring and clips behind already so the extra wire was easy to tie-wrap to them. Not the most discrete of things but it doesn't look too bad when you're sat in the car.
I forgot to take a photo of the sat nav unit, it is separate to the main HU. I mounted it in one of the little 'cubby holes' under the steering column. They never get used and its nice and out of the way but possible to get at to remove the SD card for the map when it needs updating.

- The microphone for the BlueTooth handsfree, mounted just below the ultrasonic alarm sensor.

- The finished installation.