I recently replaced struts and shocks on my 3.0 X5 with Bilstein Heavy Duty. Ride quality went from being reasonably comfortable to extremely bouncy to a point that I hate driving it. Every road imperfection is felt and even small bumps can send the rear up in the air. It is not only that they are too firm, I feel that they do not work well with stock springs. I was told by the retailer that they should soften up in a few thousand miles. We shall see. I do most of my driving is in the Northeast where the roads are probably the worst in the country. They might be more suitable where roads are smoother but here in the Northeast I give them a big thumbs down.