i have sirius, and have the antenna on the dash. No ground plate, and it does cut out once in a while, always in the same spots. only on back roads, never on the highways, and only cuts for a second or so. Can be annoying if listening to talk radio.............like stern or something.It did this in my 05 as well. If you want it to never cut out, you need to go up top on the roof, where that is one huge ground plate.
I can not have visible wires anywhere, so I am not running it out and up top. I know the 3rd taillight is a good spot to go out if you would like, but I just cant rip apart the interior, possibly causing squeeks and rattles, possibly get a leak through the taillight, and have an exposed wired outside.
You can make the entire antenna wire invisible by going up to the corner dash. I went to the passenger side, going to put the gps on the drivers side.