Don't give up
The Gentex HGU-55 is a really nice helmet.
Its odd that you can't find a comms specialist to make it work properly for you. Normally, I install the Headsets Inc. ANR kit into these helmets with extraordinary results, although I am in Australia, probably too far from you.
Can you explain the sorts of comms problems you are having with the helmet? I might be able to point you in the right direction.