"Needed a diff for my 535d touring as you can imagine not many companies produce such a part. Thankfully the great people at Wavetrac a part was sourced and the torque has been rained in. No more one tyre fires but controllable progressive traction that gives you more confidence than the open standard item, these work!! Ignore the forum debates Wavetrac is the way forward the parts quality is outstanding, the help and knowledge is also fantastic."