You can use a little dab of diff grease on the drive gears. That will quiet them up. Dingus is right though, the TC3 is naturally noisier than most belt drive cars. As the diff gears wear into each other, they will quiet down as well. If you remove them to rebuild the diff and don't change gears, you should mark the point where they mesh before you remove them. That way they keep wearing in the same pattern. If you don't they'll have to re-break in and they'll wear out faster.