I just received all of the parts needed for the install of my xm tuner (thanks to ted B. for the custom wiring harness). I now have all of the parts which are the xm tuner, ted's wiring harness, and the dual lead xm antenna (which I was told is the best aftermarket antenna.) I currently have the xm roady in my car and have the antenna mounted to the back speaker grille. I was wondering if my reception would suffer if I put the antenna under the dash like I did with my GPS antenna? I definitely do not want to mount the antenna on the outside of my car so if mounting it under the dash isn't an option I will probably just mount it on the rear speaker grille.