Between ours and an H&R (which we also carry) I would say if autocrossing is part of the plan the H&R springs would have an edge over ours.
As far as who makes our springs I have read all kinds of speculation on various BMW forums over the years. But to be honest I don't know. When the deal was made over 15 years ago the manufacturer didn't want to be revealed and they haven't been. But I can say they are all made in Germany by a large coil spring supplier.