Have heard back from Ducati UK;
"I would suggest you only book Noisy track days which are listed as such, usually around the 105db, such as the Ducati day yesterday at Donington or Silverstone on 31 July
If in doubt please call the circuit and check what their noise limit is on the day you choose, and ask if they have had any issues with a 1199 with OEM exhausts on their noisy days, though most wouldn’t know if they were OEM exhausts fitted or not!"
It appears clear 98db days represent a significant risk to failing the minimum noise requirements. Where owners stand with circuits like Oulton Park & Snetterton which is 102db seems to be a grey area.
For me, Norfolk is a long way to go to be turned away with OEM pipes!