I saw this thread over on Rennlist which has some pretty useful tips on the installation: Full Rennlist thread
(not my information, hope it's ok to post here)
take your time on the wiring of the flex cables, I had to go back and reseat them a couple of times so that everything worked. Another big big tip, you have to separate the bottom half from the top half of the head unit after you remove the faceplate. This seems to bite everyone who is doing this mod. There is a very easy way to do this. remove the three screws as pictured in the video, then use a large flat bladed screwdriver and look to the left and right sides. you can see the two channels on each side where the top and bottom pressure fit together. insert the flat blade horizontally between the top and bottom right where you can see the pressure fit channel is and give a slight twist. do this on all four areas and the sucker just falls apart.
If you have the XM module you will notice the risers aren't high enough, you can either just use two risers and let it rest on the XM board, or go to amazon and order some more risers to clear the board
the video cable (make sure to plug in with pins facing UP), to route it I unscrewed the mount for the XM plug and ran it through that hole, then screwed the mount back on (it is not longer seated at bottom, but holds good enough)
This is a big one - after you do all the mods to the head unit, plug it back into the existing cables like you didn't mod it at all and check that you still get video and audio, if you don't it's the thin flex cable 9 times out of 10.
If you have Bose or Burmester you have to remove the ORANGE fiber optic pins (its slides out as a 2 wire plug) and plug that assembly into the 48 pin extension dongle or you will get no audio
On the Cayenne you can tuck the entire assembly rather neatly behind and below the head unit, there is some sound deadening foam you can place it on and push down.
To power the unit I use Fuse 3 on the left side (driver's side), it is the horn fuse and it is switched. I got some of those fuse adaptors from Amazon so it is plug and play
Have your iPhone FORGET the Cayenne's bluetooth or the car and carplay will fight for incoming phone calls.
I ran the mic right to the base of the left center vent, works pretty great there.
Run the LVDS (video) wire through plate that is on the yellow plug on the left. that way you don't have to cut any holes in the frame
In the cayenne, all the components and wires tuck very neatly in the cavity at the bottom rear
Took me three times of installing and pulling out the head unit to get everything to work. I find that taking it to my desk inside the house forced me to take my time, especially with the ribbon cables.
Separating the two halfs of the head unit is difficult until you figure out that you can use a large blade screwdriver on each side (you will see the two pressure fit gaps on each side) put the flat blade in the channel and twist in each four, the two halves just pop apart.
- after you install the parts, test it as if they weren't there, and make sure you have all functionality. then wire up the dongle, move the fiber optic (orange) cables to the back of the head unit 48 pin attachment, plug in the car play and test it, then install.
I mounted my mic to the left of this vent at the bottom, removed the clip and just had the dash panels hold it in place
it works wirelessly, but for when you want it wired i ran the USB attachment down the left side of the centre console with just the attachment poking out.