I've heard the same so added an audio filter as well as radio and comms grounding straps. Hopefully it helps. Been reading through a lot of Rugged's literature. A good bit of it is in regards to reducing interference and electrical noise. For instance, apparently it's a bad idea to coil up any extra antenna cable. Either route it the long way around to use up the excess or cut and shorten. Might be obvious to some but I'm brand new to this so really trying to pick up on as many tips as possible. For some stupid reason, the headsets have a different plug than the com unit. I got 12' adapter cables which would've been needed if the unit was in the dash. Now that it's between the seats, I could easily get away with a much shorter cable. Which again, would probably help eliminate noise.Most of the intercoms I've used have a lot of electrical noise, which is a bigger issue than exhaust.