Kia, for instance, advises against installing any after-market equipment whatsoever in their vehicles, which is certainly to avoid any responsibility for incompatibilities that might adversely affect the vehicle's operation. In other words, if you do any sort of installation of powered equipment in the vehicle, you're on your own.
I bought a 2013 Soul, and didn't see anything in the manual about adding radios; I asked the salesman, who (of course) didn't know, but he introduced me to the service manager. The SM said he wasn't aware of any technical service bulletins about adding an HF radio to a Soul. He promised that he would check and email me if he found anything relevant. My feeling was, "they didn't say not to so it must have been OK." :-) As it turns out, I've never had any trouble with a radio in that Soul.
