Thanks for all the replies guys. Yes, Darryl is right, it was at a commercially organised Car/Bike tack day during the week at Eastern Creek here in Sydney, Australia. The sensors are located at 300m before turn one, about half way down pit straight. I have not had any static other type of noise measurement done on the car, so cannot comment. Certainly a large amount of the noise is induction related. At the time I was at around 7500rpm and the speedo was reading 145mph (which since it is so inaccurate, it was probably more like 120mph.... just one more thing to get looked at!). In any case, they were fine about it and I just promised to not rev it so much at that point on the track.
I was just hoping that there was an easy, quick and cheap (is there ever such a thing?) fix to reduce the noise slightly which leaving the power untouched. It would certainly help when driving on the road.
Once again, thanks for your comments.