I have a 2004 545i w/ Sport Package. When would you recommend replacing the factory "sport shocks"? When do you know when it is time? The car drives/handles perfectly. But when I go over slight bumps (i.e. speed bumps/humps) I can hear the shocks making some sort of noise. Again, the car handles and drives flawlessly. Should I be concerened? The car has about 63K miles on it. Any help wold be appreciated.