Curious - I originally (a LOOOOONGGGG time ago) complained about interference due to the use of 27 MHz FM CB in my Mk 1 installation: it turned out that the problem was with the installation of the CB Transceiver in my car, which I sorted with a power line filter to the CB and the empeg. I haven't had a direct problem since even when using an unshielded transceiver in the car since.....