Spent several hours on my XM install (pre-wired 2003 coupe). I wanted the antenna on the back shelf in place of the left side child restraint, but did not want to run the wire behind the back seat. After a couple of hours of poking around with a stiff wire in the restraint hole in an attempt to find a passage into the trunk, I finally gave up. However, I did notice daylight when I looked in the restraint bolt hole through the rear window, and sure enough, it came out in the trunk area. However, I had to remove the antenna wire plastic connectors in order to thread the wire through the bolt hole.

Next was the tuner. Although the coupe was pre-wired, the connector had about 2" of play - no way to mount on the back of the lower trunk wall. I put some wooden strips down next to the amp using the double sided sticky stuff, then stuck the tuner to the wood. The wood was needed because there are two screws protruding from the trunk floor which prevented me from simply placing the tuner on the floor. I may eventually build a stand with legs (similar to the amp), but it seems to be secure for now. Overall success - no signal problems even inside my garage. BTW, my 35% tint is not metallic.