I've been running Ford Racing springs with Bilstein B8's for 4+ years and over 50K miles. Recently I started noticing that the car seems to sit lower than it used to, especially at the front. The ride feels more harsh too, though it might have something to do with our crappy Illinois roads... I didn't take any ride height measurements back when springs were new, so can't really compare the numbers. So, question is - how long do the springs usually last, particularly lowering springs? Is it expected to get lower ride height and more rough ride with time?