OK - I installed my new Prothane transmission mount without a hitch. Now I am noticing some vibration or "harshness" between 2000 - 3000 RPM. Is this due to the stiffer polyurethane mount? Will it wear itself in eventually?

 

In my own experience, I have found that the vibration stays with polyurethane Tammy mounts. The previous owner of my car installed polyurethane mounts because he "didn't like " the stock ones. I only have vibrations around 1100 rpms when the engine is cold.

Stock seems like the best way to go.

 

Poly is stiffer. More vibes are going to get through.