Another possible option, though I'm running it on my 35i, as are a few others. Not sure what the 3.0 clearances are. May require opening up a couple bolt holes just a smidge. Otherwise a strong and good-looking product.
http://www.ebay.com/itm/Luxon-Strutbar-for-BMW-Z4-E89-/191988509095?hash=item2cb36829a7:gIQAAOSwmLlX9bS-&vxp=mtr
Filippo