Hi yes I did fit the lip spoiler, it was a chinese one of ebay prepainted..very dubious but i was feeling stupid so pressed the but button whilist the wife wasn't looking.
Arrived 10 days later well boxed.
Paint match is not perfect but I don't like the black ones.
If the rest of the car had the same weight fibreglass then it would never fly over humpbacks, but its only a small piece.
Will get it repainted perfectly over the winter.
http://www.ebay.com/itm/PAINTED-REAR-TRUNK-BOOT-LIP-SPOILER-FOR-BMW-E89-Z4-Roadster-2009-2010-/332180113492?hash=item4d577a4854
This seems a later version of the same type..