George,
I apologize for not answering this before.
There is very little RF noise on my plane. I am not exactly sure why since I did not make any efforts to shield my plug wires, ect. Rememberr that the KFM 107e is CDI so that may help with RF supression. The guys that have done the 185 CDI conversion may have some insight on that one. I use an ICOM A-14 handheld radio and have it set up through an intercom that is powered by the electrical system. My antenna was removed from my brothers series III and it's connected by some RG8 and mounted on the leading edge of the tail section. If memory serves correct, the RF noise was worse on his Lazair so I don't believe that his antenna is anything special.
Dave