I hit a huge ass Chicago pothole and broke the left side mounting point for the strut to firewall bar, along with mushrooming the rubber upper strut mount.
I ended up ordering this since it doesn't use the factory bar mounts on the top of the struts:
http://www.ebay.com/itm/BMW-Z4-E85-F...25a9ba&vxp=mtr
I've been happy with it. Not as pretty (or expensive) as the strongstrut setup, but it seems to work well for my daily driver. Shipping was actually pretty fast as well.