Sometimes replacing shocks is a joy, sometimes it's a nonevent. I've replaced Bilsteins at 125k a couple of times and felt no difference in performance whatsoever. I once told a Bilstein U.S.A. rep that I was changing shocks at 125k and he was utterly baffled that I would be doing such a thing. Conditions do vary - but there's no reason to change them if you don't feel any degradation in performance - the new ones won't feel any different and you'll be out around $400.