The message is not getting through. Loud bikes must be excluded. The sad thing about Conondale nats this year was that at the riders brief on day 2, the track Steward was forced to tell riders who passed machinery with mufflers on, to refit them, as it was so obvious they had removed their muffling immediately after. I went for a walk between races, and saw quite a few bikes, mainly 4strokes, with no muffling whatsoever.
On the last club meet before the Nats, the BMCC had a noise meter so people could see how their bikes went. I spent an afternoon rebuilding the muffler on my Maico and tested 93/94 db. Very worthwhile, yet some would say, after what they saw & heard at Conondale, what a waste of time.
Mike