I used the stoptech kit on my previous car and it also failed after about 15 track days. Stoptech would not warranty it because of "track use." That blew me away, as that is what they market their kits for.
This is the only BBK I would consider. It is in a totally different league than anything Stoptech makes, and I have a set on order. I absolutely can't wait to get it.
http://f87.bimmerpost.com/forums/sho....php?t=1264385