The F/X helmet maybe be oversized, but with some key modifications, it look much better and fit the FISD deployment specifications.
I finally completed my mod's today:
1. Blue tube stripes
2. Stunt configuration: green flat lenses with 8 teeth
3. hovi mic tips
4. Updated brow trim for clean look
See pics below, the third picture is my F/X next to my RT for comparison...
Thanks to Stomper (hovi's), SuperTrooper (mic's in hovi's), and Machorascal (brow trim).