PST or Bergman LCA bushings and pivots?

I used polyurethane on mine. I've done extensive design work with delrin and a few other plastics and I wanted to have SOME give in the suspension. I don't want every little bump and jolt transferred to the rest of the car.

Besides, I've seen delrin fracture, especially when cold, and I didn't like the idea of that in an application that sees....impacts.