Is it possible that a sway bar has become disconnected? If the rear sway bar is disconnected then the steering will respond slower. However at a slow speed and turning the steering 90 degrees into a driveway I cannot imagine how you could have to turn the steering wheel 180 degrees. I vote for something going on with the tires, especially the guy who put on the Bridgestone MY02 tires and noticed a difference after. New tires have an oily coating on them and the tread is deeper, all of which slows down steering response. At first I would vote for control arm bushings being the culprit but 25,000 miles isn't much, plus the change would have been gradual. This whole thread is crazy!