i purchased a Bose A20 and then took it apart to install into a Gentex SPH 5 helmet, I know it’s not an approved setup and the warranty is voided, I just want good noise canceling. I am flying a Chinook, which is very loud, and the noise canceling is fantastic on the ground and in forward flight. However, I am doing fire fighting and when we are lifting 20000 pounds of water, the thump of the blades in the hover, and increased engine and transmission noise overwhelms the noise canceling and I get the “woofing” which hurts my ears. The Bose earcups are fitted inside the Gentex earcups to protect them, but I have made cutouts in the back to expose the Bose ambient noise sensors, that seems to be working fine. I also wear glasses which does not help with the seal of the earcups. The Bose earcups seem to be quite small and my ears don’t fit inside them very well, I don’t think my ears are overly large either. Is there anything else I can do to make this setup work better?