All four of my rear control arms were badly bent on my mystique. I removed the rear two and straightened them. I placed them on a big anvil, and beat them with a big hammer. I finally restored them to a near perfect condition, and they haven't changed since I reinstalled them (that was about 1 year, 20k miles ago).
The forward two arms (still on the rear of the car) was a different story. I can't get them off, so I'm still driving with bent arms. I have done what I can with various tools to remove some of the bends, but they still have a lot of room for improvement. Suppose I'll have to someday drop the subframe to replace the arms.
