The FNA X Stream (http://www.fnaheadgear.com/
) is a pretty nice helmet. I think there was a thread about adding a vertical bar to this a while back. I think the aftey bars for the Gus fit just right.
Ask Faron with FNA if you do want to do this, I guess he will do it for you if you have him make you a helmet.
I love mine (no bar added) and have been using it for a few years.