I have a Pioneer Avic X1 installed complete with a 12 disk changer in the boot, (trunk to the USA guys).

Took a few mins to lift the trim, be careful not to damage it.
The sound travels from the main (ultra thin 40gb unit) which I have placed in the front passenger side footwell to the "hide away" Pioneer unit using a very expensive audio lead.

Sounds quality is superb and I am very pleased with the unit and the installation... this really now does complete the audio in my car.