When I ran my TM moto for part of a season, it was quieter than my Honda CR125. Using some junky silencer off the TM pipe. Repack your silencer with some fresh packing and it should be good. We had a 96 db limit and I never approached that – but did get in the 93-94 range with the Honda.
If a good silencer is not enough to meet sound adding an airbox will help a good bit. Just keep in mind it will most likely result in you needing to change jets.