Dan... AST has EXCELLENT ride quality... I have a set on my E30 M3. I could drive it on the street to work... yet with 700/850 spring rates, it's set up well for the track.
It doesn't hurt that their headquarters for USA are here in DFW and that I know the owner personally..
They aren't infallible.. but they make excellent products, and they back it up with great service... ask Eric Heinrich how they came thru for him at Ofest year.
Lone Star BMW CCA Chapter president, Chief Driving Instructor - LIFETIME Member # 119366
Past: 1991 BMW E30 M3 street car ; 1988 BMW E30 M3 track car http://ofest.bmwcca.org/