I'm just wondering why you are having traction issues with a 530i !? yes, it's rated at 231 bhp and 'can' spin it's wheels if provoked that way, but overall, it's not that fast! after all, there's two more E39 models higher! Could it perhaps be low tread on your tyres and/or not very grippy tyres ? see if changing to known grippier tyres solves your issue better? If you are anywhere around here/West London/Heathrow/Slough, then do pop into Bird's garage in Iver where they do uprated differentials etc.