Lyric, I just want to agree. Something seems a bit "off" with the turret sound.
It appeared default was at 20... but when I hit "test sound" at 20, it sounded more quiet than the turret I was actually using. I set it to 10 and hit apply, and the turret sound went away altogether. Launched the next GV and the turrent sound DID seem a bit more quiet, but not nearly as quiet as "test sound" would have me believe.