Otter, I stretched my DCB/MonCal helmet out with a hair dryer. I warmed it up, one side at a time, then jammed it on my head repeatedly and held it there until it cooled off. (Be careful, you can heat up fiberglass hot enough to scald your head.) I also dremelled out the front lip a bit.
Worked. Still gives me a headache wearing it longer than 7 hours, but I'm tuning it.
Deunan "Shiruba"