680MAINE,
Something that I haven't seen mentioned is to stay as far away from the computer and it's associated wiring as possible. NO idea where the @#$ computer is located in a Dodge, so staying away from it may not be all that easy.
Filtering, by-passing, and all that stuff certainly won't hurt! The radio system, not the computer, since the car manufacturers sort of frown on messing with their stuff. Those manufacturers are sort of 'pessimistic' with their RF warnings, but a little 'crowding' may not be that bad. If the Dodge is still under warranty, don't mess with their stuff. If it's out of warranty, only mess with stuff you can afford to replace, you know? I wish him luck.
I also won't make the 'normal'/standard/typical comment about letting friends drive Dodges...
- 'Doc