I recently purchased a new gas powered truck and find that after installing my radios I am getting RFI interference. It appears to be coming through the antenna and coax. The placed that installed the system determined this and determined that the spark plugs or coil pack are the culprit. I am looking for ideas on how to get rid of the noise. It is a snapping or popping static that does not seem to vary with RPM. I have a number of ferrites that I am willing to try. Where would these be placed--on the coax by the radio,by the antanna on the coax, or on the wires going to the coil pack. Is there possibly a better spark plug than the OEM. Any help is appreciated.