Went to Castle coombe circuit yesterday to have my CAV GT40 noise tested so that I could attend a track day next week. It was 110db! at 4500rpm whereas the limit is 100db. I am a little surprised since my car was 101db at 4000rpm at the SVA test about 6000 miles ago. Does my muffler need repacking?. Your thoughts would be appreciated. Now I am thinking of booking a track day at Silverstone,what is the noise limit there?.