At the tracks I’ve ridden there are no noise restrictions (COTA, road Atlanta, Barber). I did manage a couple of sessions at Laguna Seca by just backing off the throttle at the sound meter.
That said, it does scream! And what a lovely scream it is.
Re: rebuilds, I’m sure factory team doesn’t do rebuilds, i.e. Aruba, but I can guarantee that every other team that utilizes the bikes do, WSBK, BSB, MotoA, etc. I’ve met the man from Corse who is charged with the rebuilds for these motors. Then again, there are rebuilds and then there are rebuilds.