Have a 95 T/A A-4 w shift kit. Just had the stall replaced from a 2200 to a 3600. Before the swap the car hit 2nd gear real hard and third was crisp, now it shifts real smooth through all gears, buit it sure gets up in RPM's a lot faster. Car also vibrates more now. Original stall was 12 inch, the new one is 9.5. I have poly motor and trans mount.

 

The stall will make the shifts feel softer. The stall isself should not increase vibration but will increase the average RPM at low speed. The poly mounts you have while strong are well now for transfering vibration , Theres a very good reason GM made the quishy ones and it wasnt just to be cheap they dampen vibration very well.