I have the PAL w/o XM and it works just fine. Its pretty easy to install, you have to remove the stereo and plug the PAL harness into the back of the stereo and then the factory harness into the PAL harness. The PAL harness then runs to a module that you mount on top of the ventalation contol box. From the module you run a short cable into the glove box that attaches to the Ipod. Like I said, I dont have XM so I cant vouch for how well the PAL works with XM but as I understand it that is where the problems lie. The only problem I ran into was that the temp door lost its calibration and it took about of week of messing with the temp knod for it to recalibrate. When the calibration was off it would blow full hot on any setting except all the way to the left and then it was full cold. I tried to recalibrate it w/ my Tech2 but couldnt find a setting for it.