Figured i would throw my experiences out there...
I've had interference issues for a while... to be honest i haven't even used it in a while.
I've taken everything out of the car, used it inside, bought ferrite split beads, isolated components, ... the works.
What I have found is that something from the carPC itself is causing the interference.
I powered the computer off an ATX bench supply I have, and there was definitely less noise... which points to the M2-ATX as the problem. But there was still some problems.
Something you should try to see this is to control your Visteon with the control brick... have your computer running, and then shut-off your computer. I almost guarantee you will see a signal boost or a quick lock-on to HD. It worked for me every time.
So that's where I'm at. I haven't really messed with it lately..... but darn that RFI!