This is a word of warning following my experience at VSCC Pom at Silverstone this weekend. I was in an ex Kuhmo Cup E36 M3 that has done over 200 races, so it is a car that has been checked once or twice in the past.
Anyway, within the last few weeks it seems the MSA have issued a "clarification" to the scruits about roll cage mounting of the main hoop and front stays to the floor. They are insisting on a foot welded to the main tube that is then welded to a reinforcing plate welded to the floor. It has been practice for many car builders to build a "box" for the cage to sit on about 6" high up from the floor for increased strength. What the scruits are now saying is that it is unacceptable for the main tube to be welded to the top of the "box", instead there must be a foot on the tube welded to the top of the box. There is no specification for the size of the foot, so in theory it could be the diameter of the tube, but in practice you may get rejected for that. The alternative is to have a reinforcing plate under the box.
If in doubt read this
http://www.awmmc.org.uk/images/infor...crutineers.pdf