Works just great that way. I had mine stuck to the front speaker, since the mount was magnetic, while saving up for the integrated solution. There tends to be a slight more interference if you're say, stopped under an overpass - or at least, that the signal is more likely to drop in those kinds of situations, but for standard driving it works fine. -m.
You can also use a "home" XM radio antenna on the dashboard. It does pretty good there. You can even put a "home" antenna inside the center console; as long as the signal is strong that also works (though with weaker signals you'll get a lot of fading from overpasses, tall trees, etc.).
I just bought the Delphi Roady II. It has a wireless FM modulator built into it so there is no need to take apart the car to install it. It works great, I just plug it into the power outlet and put the antenna on the dash. There seems to be some metal under the dash that the magnet in the antenna sticks to and that keeps it from sliding around. (Someone please tell me if you think I am doing something that might harm a component under the dash.)
