Replacing the lower motor mount on my '97 Lumina made it a different car. I don't drive it much, but noticed a big difference when I test drove it. All the vibration I attributed to just age and 150k miles and maybe some suspension wear went away. But my wife is really ecstatic since it's her daily driver and she's the one who said it's a different car now. My biggest impression from doing the job was seeing that rust has holed the rocker panels, about 2" on each side. I normally make sure I don't look there, but I couldn't avoid it when I did the mount. The original mount was disintegrated and the new mount lifted the right engine side almost 3 inches.
--Vic