I have always used D.I.D. for racing & it has never let me down, I have a tight spot on my 748 chain at the moment & will be replacing it over the winter, I have been advised by Nelly to try the Subaki Sigma chain. As B&C Express is only 5 miles up the road I will be getting it direct from them.
You can get all your Arrow, D.I.D, Subaki etc direct from them, you do not have to go through a dealer, I do not know if they are on the DSC discount list though.
Chris.