When I bought my helmets I selected specifically with integration with the HD intercom system in mind.
I tried numerous helmets and the best, in my opinion, is the Shark Evoline if you like a modular helmet.
The mic sits nicely at the front of the helmet with getting crushed or forced in to your mouth.
Trimmed out some of the foam and the speakers fit perfctly. Only thing that sucked was the fact that HD do not put small connectors close to the speakers, so for a neat run I had to cut the wires, feed through the helmet lining and then resolder, but all in all very happy with the result