I replaced my non-JBL speaker system with a Beat Sonic amp, JVC dash speakers, and Morel MKII speakers for the doors. Spent roughly $600+ through a Beat Sonic dealer and Crutchfield.
Big difference in sound quality and very satisfied with the set up. I listen mainly to classic rock from the...
Wouldn't stuffing some RFID cloth into the shark fin cover block all signals?
GPS and radio/music can be through your phone. Or if you're old like me, music through thumb drive.