Anybody have problems with muddy sirius sound? I have an 09 Mustang Bullitt with the Shaker 500 system. Every other source sounds great (ipod, FM), but siruis really sucks. Sounds really muddy is the best way to describe it. I hooked into the antenna already on the car which should be in a fine place (on the trunk). i dont remember the stock head unit sounding as bad. ohh, and the unit is the avic 700bt