Did this the other night. Had been sitting on it for a while waiting to get short shifter so i could install both while i had things apart. I took lots of time (about 3 hours including trip to radio shack) and had zero problems. The instructions are very good.
Only thing i noticed is that i don't think it's necessary to remove the outside 2 of the 4 screws that are removed from behind where the face plate would be to get the disc changer out. THat probably doesn't make any sense, but it's not important anyway. Even if it's not necessary, it only adds like 15 seconds to the install time, lol.
I didn't bother with the GLI yet. Figured i'd try it out and see if i needed it since apparently some people do not. So far it's fine. I have noticed a couple times some hiss when the music is paused, but not all the time. If it becomes a problem i'll hook up the GLI.
Thanks Jazzy :-)