i just replaced my front rotors (91 m5 w/ 50k) but still have some vibration during hard stopping. does this sound like a bushing concern? what happens when your rear brake rotors are warped, what sort of vibration does it make? What half-life do rubber bushings have, everything suspension-wise on this car is original? After eleven years should the font struts be replaced? rear self-leveling? the rear shocks show no leaks and work flawlessly. would a bilstein replacement sport shock kit w/dinan springs improve handling? Thanks