For sale is a pair of Vorshlag Polyurethane Competition Motor Mounts for E30 M3 S14. Not certain whether they are 70 or 85 durameter, but they are rather stiff (there is a little give in the material when I squeeze hard, but I'm talking really hard to the point of hurting your fingers). These are in never used condition. I purchased them in the hopes of upgrading one day, but decided not to considering the car is never driven hard so would not take advantage the benefits this upgrade provides. Asking $160.
More info on Vorshlag here
Actual units for sale shown: