I have a 2007 Mustang GT coupe, how well would my GPS work if I mount the antenna in the trunk? I've seen it mounted between the rear speakers on the back panel, but didnt really like the look of it and wanted to hide it somewhere. A friend of mine has his in the glove compartment, which is where my slim PS2 is so I don't have too much room in there between the system and wireless controller. Any other places I could mount this where it would be out of the way and not visible?

I would recommend putting in the corner of the dash board right by the windshield or in the back by the back window. Putting inside a compartment could affect the reception on it. It's hardly noticeable if you run the wire through the dash and just have the black box on the end of it showing. It's still a very clean install.

Agreed. Think of it like a satellite dish. The better line-of-site to the satellites you have, the better your accuracy will be. Trunk is a bad idea