So quick update.. I've now tried everything ever listed in any forum I could find and it has not resolved the issue. Tonight I took off a part of rear trim that surrounds the roof mechanism on the rear deck as someone mentioned this previously, it was not that. I also masked the pin on the rear roof clamshell (that inserts into the slot on the rear deck) and this made no difference either. The more I drive and listen the more I think that its the mechanism itself on that side that clicks when the chassis twists and rattles when going over manholes etc. If this is the case it will likely be the dealer that has to sort it, but I've not quite given up yet...
Black Sapphire BMW Z4 sDrive35i
Mods: HiFi Tweeters Stubby LED Halos & Front Indicators DVDInMotion SmartTop 313 BMW Performance Alloys LCI Repeaters http://goo.gl/PF4nSz