Pictures of a GT installation
Here is where I put an UltimaXL on my 2007 GT. This location required grinding down part of the seat pan near where the corners of the Baehr would otherwise interfere with it. One of the attached pictures show the ground area on one side of the seat pan. I was worried about overheating the Baehr given its proximity to the oil reservoir, but I've done two cross-country rides with ambient temps in the 90s (max was 98) with no problems so far.
I have it managing a two-way radio (Ham gear, seen in the picture), a Baehr Blue Phone (paired to my cell phone), and a direct connection to my BMW Nav III but the audio from that is way too low to be useful. Baehr tech support said that a direct connect to the Nav III will not work but I have not followed that up since I don't have a pressing need for that audio feed anyway.
One problem I did encounter was that if the Baehr's case touches any metal (notice the foam padding underneath it to prevent this), the audio was very noisy. Isolating it with this foam cured that.
Performance has been excellent.