I installed poly bushings long after doing everything else in the suspension: Eibach springs, Bilstein Sports, 22/19 bars, 195/50-15 Pirellis, and TEP braces. IMHO, the poly bushings were nothing but a major improvement over the old rubber. Now, that's not to say that new rubber wouldn't have been, but I like the urethane. They are easy to install, don't squeek, and make the whole car nicer to drive. I've done long highway trips in the car and don't find it unpleasant at all. It is stiff, to be sure, but not tooth-jarring. The improved precision in the steering and suspension is well worth it.