You´d better look for a good passive headset with decent noise isolation, helicopter sets are meant to have this. And once you got a set at acceptable price have a look inside, easy to do. Most likely you find some more space for extra padding the plastic shell and hopefully noticable success. It is a bad idea to increase sound level from loud to unbearable by getting an even louder radio hooked to a poor headset.
For getting an idea look inside noise protection headgear that is used in high noise workshops and modify if necessary.
Vic
