ST are made by KW. So whoever said that doesn't know what they are talking about. They have soft springs for doing regular track days, periodically they may be okay. They also don't have camber plates.
The Flex A's come with camber plates and have hydraulic bottom out bumpers. They are pretty good for the price.
Here is the CSG Flex A owners thread full of happy customers.
https://www.ft86club.com/forums/showthread.php?t=126107