After reading your review I can't help but continue to scratch my head and wonder why people keep buying the H&R coilovers for their Z4M's instead of going with the TCKlines or Ground Controls.
Sure they cost more, but you get a kit that handles even better than the H&R's, and they ride more comfortable than stock suspensions. And they come with camber plates. If one's already going to spend the money for a set of coilovers and for the install, corner balancing and wheel alignment, why not spend a little more and get the best of both worlds instead of having to put up with the crappy ride comfort.