I gained a lot of information from this post, so I thought I should share my experience and perhaps help some others. My car is a 03 996 with the base soundsystem. I installed a JVC KW-AVX840.
The current version of the Euro Motorspeed kit has a sleeve with flanges on all four sides which is designed to make installation centered in the opening easy. I am guessing that not all years are consistent on evenness of the opening. Mine were not even with the top and bottom being more recessed than the sides. I needed to shim the upper and lower flanges to make it work. Once I shimmed it, the sleeve worked reasonably well. Bending tabs cut into the sleeve are supposed to hold it in position. It can shift around if pushed, but in practice, it seems to work well.
I had some difficulty getting the climate control unit to fit in the lower slot. I found a posting on Pelican suggesting that four small ridges in the white plastic on each of the back corners was the problem. I trimmed those off and it fit, tightly, but I figured that that was good.
I was confused by the aluminum support bracket which is about midway inside the housing where the radio and climate control unit were. Based on some posts here, I thought that it had to be removed, but I saw no obvious way of doing so. Trieullionaire answered my phone call right away (he has both times I called him). He said that the support bracket should stay in, but that the black horizontal pieces attached to it needed to be removed. These pieces form a bracket into which the top of the radio slid and which supported the climate control unit from below. I tried bending them up out of the way, but the metal is pretty thick so that did not work. I put a grinding attachment on the dremel and removed the rivets holding the pieces on. This took a while, but the pieces came out.
I wanted to mount the microphone in the factory location which meant getting the instrument panel loose. At least on my car, removing the bezel surrounding the hazard switch was more difficult than the instructions I found suggested. Prying it off looked like it was going to mark the leather because I could not get the bezel to lift away at all. I found a suggestion somewhere on the web of removing the flasher button and then putting a screwdriver in one of the slots on the interior sides of the bezel and pulling on the screwdriver withpliers. That worked, although it did take several minutes of searching to find the bezel after it flew off at nearsonic speed.
My next problem was running the microphone wire. The plug end had a 90 degree bend in it whichwould not make it through any of the routes I could find in the instrument cluster. I cut the wire, ran and did a splice. Those wires are very very small and after my splice, the microphone was not working at all. I then bought a Olympus ME-52W Noise Canceling Microphone. Again, I did a splice, but the microphone sounded terrible from the factory location. I then placed the microphone in the space immediately in front of the steering wheel. It was still terrible; lots of distortion. I found a microphone volume adjustment on the JVC unit and got it to work well enough to be understood, but it is not really very good at all. The microphone does agood job eliminating background noise, but my voice sounds very distant. I may need to try another microphone. In hindsight, I should have completely removed the instrument panel, but I did not want to unplug it.
One of my bigger problems was that the JVC KW-AVX840 was sitting either too far in the dash or too far out depending on which mounting holes I used in the brackets. I first thought that I could use the deeper position and then use longer screws which attach the mounting bracket into the sleeve and that would allow me to get theunit forward using washers to create some space. As always, Trieullionaire was very helpful and sent me the specs on the screws so that I could get longer ones. If I took that approach, I was going to haveto do some major surgery on the bezel from the kit, so I looked at other options. I noticed that there were mounting holes on the brackets roughly in the right position but which were located a bit off vertically, so I elongated the holes with a Dremel and now the unit fits reasonably well. The bezel is meant to be held in by tension, but my cupholder knocks it out. I should trim it a bit and find another wayto mount it, but my patience is gone and I am done messing with it, at least for a while. I never use the cupholder anyway. Overall, the unit mounting and the bezel are not quite even in depth, but they are close. I am reasonably happy with it. When my tolerance for tinkering with it is restored I may take it out and adjust a few things to make it fit better.
Trieullionaire suggested tapping the illumination wirefor the light surrounding the lighter for the illumination input to the new system, but since I was removing the center console to run the USB cable to therear console box, I tapped the wire to the ashtray light instead. It was more accessible.
When I went to reinstall the instrument cluster, I discovered that the clip into which the screw next to the hazard button was gone. Luckily, I had a replacement clip which fit.
I have the alarm beeping problem with the radio removed. I tried to locate the wire which others have mentioned which needs to be grounded in order to avoid alarm problems, but I cannot find the wire. I wonder if I moved it while trying to remove the support bracket which I did not need to remove. I could not see anywires on the left side except those that run to the PSM button and the wiper rheostat. Perhaps the alarm portion changed when they went to the MOST bus system? This is very frustrating. I would like to find the answer.
If you have a MOST bus car, but the base audio system, that is, one with no separate amp, then the MOST bus connection to the CDR23 is not connected. Euro Motorspeed sent a kit assuming that I had a separate amp. I called and Trieullionaire very promptly send a replacement harness wired sothat the new head unit powers the speakers.
If you use the phone prep harness for your switched power, the feature where you could listen to your sound system with the key in the ignition but the car not on no longer works. The key now has to be in the on position for the sound system to work.
I ran both a USB cable and a JVC specific cable under the center console to the compartment in the back of it. I notched a hole at the bottom of the front wall of the compartment for the pass through and then taped the wires in position to hold them in place for reassembly.
This was a lot of work to get done. I suspect that a pro could have positioned the unit better. Unlike other projects where I felt good about having done something myself, I don't feel that way about this one. Now I wish I had looked harder for a pro to do the installation.