FST = lower level KBS. FST comes from FEMCO. Far East Machinery Co. http://www.femco.com.tw/portfolio/fst/?lang=en
IMO since I have worked with FST since it's inception the QA is better than TT lower price range same-same apples to apples in price range. All depends on what weight and shaft profile you are seeking.
For quality Nippon, KBS and FST are better steel IMO.