I am currently installing Hal shocks and springs, and was thinking about swapping out the stock rubber bushings in both the upper and lower control arms with prothane polyurethane bushings. What is your experiences with these bushings? They look pretty impressive. The stockers appear to be in good condition.

 

I replaced every bushing under my car with prothane. Got 'em, love 'em.
Just be prepared for little more road noise.

 

I put poly in all locations except the motor mounts, I have them sitting here just have not installed them yet.
Tightens the car up alot but you do feel everything you run over, I think I can feel the car running over a gum wrapper but it just might be me.
The best thing about them is they never wear out, no automotive chemicals effect them so they pretty much will last the life of the car.