"How do the motor risers work with the new feet? Are they part of the footer upgrade?"
They are 3 brass machined to order feet securely attach to a (acrylic?) platform. On top of that there is a carbom fiber disc for additional dampening. Tell Larry what your TT is and the shape of your motor (round or rectangular) and he'll make you everything to order. The riser is extra $. Here is a link to a couple pics of the feet:
FEET
Note-
My TT motor riser is NOT in these photos.