Had new upgraded wishbones fitted at the factory yesterday 26.4.13
Driving back to Stratford upon avon I suddenly realised something was missing - Bump steer!!
Well lets say its very noticeably better/almost gone!
The tracking had to be re-done at the same time so this too could well have added to the overall "fix"
The four new wishbones are of much thicker tubing - and I guess - not being an engineer, that the whole of the front steering /stabilty is now much stiffer/firmer.
Anyway hope this helps - and I would recommend this upgrade to M3W owners.
New cars are all now fitted with the upgrade BTW
And yes I was charged £70 for the labour -but overall a happy chappy