Igofastr, that's a good question, especially the question of if they will allow it to run in the Challenge series.
The FIA is scheduled to be released after the 818 at this time, so it could be 6 months to a year. It's a good question to raise now though to see if it could be included in the 2013 racing year...
I'll pose the question over on the FFR Challenge series forum. I also passed your comment on to Dave Smith. Personally, the FIA is my favorite shape. To see a challenge series chassis with an FIA body would be AWESOME!
