My car is almost 2" (50mm) lower than it was as a stock Xi (thanks to the KWV3's). I ditched the RF's in favour of 19" PS2's just before I changed the suspension out .... . Most (if not all) of the banging is due to RF's. That being said the car cannot be safely driven in any sort of aggressive manner with the stock suspension.
'11 550i | AT | Dark Graphite on Black