Squelch Setting for Flightcom 403

I asked this question over in the comm thread and had a bunch of lookers but no comments so I thought I'd ask here also...

I have Garmin SL40 and Flightcom 403 in my RV-12. When I bought the plane from the original builder the comm radio had a terrible squeal when transmitting. A kind sole on VAF suggested reducing the side tone and that solved the problem.

I have one last issue with the audio system and that is the squelch setting for the intercom. I find that I need two settings ? one for ground when the cabin is quiet and a higher squelch setting during takeoff and cruise flight when the engine is producing power and noise is generated from wind. I don?t know if this is common. The difference in squelch setting is about 90 degrees of knob rotation on the Flightcom 403. I can live with this but it would be so much better if I didn?t have to fiddle with the intercom during change in flight modes. Any help appreciated?

Is the other headset sitting on the passenger seat or is a passenger wearing it? If laying on the seat, set the intercom to isolate because the mic picks up more noise when not being worn. Is the mic a noise cancelling type?
I usually do not have to adjust the intercom squelch very much, definitely not 90 degrees.

Problem occurs when passenger is wearing headset. I have LightSpeed Zulu headset and passenger is a Dave Clark.

Missmatch in headsets could be part of the problem.
Flightcoms documentation discusses it

I suggest that you use "mike muffs" if not using them already and be sure the mike is positioned very close to your lips -- this helps reduce external noise. Headset brand mismatch is also an issue per comment above.