well, Eric said STU so the 2.0L limit is not important. other than the really big engines in ITS (TR8 and V6 pony cars) and the old datsuns still running around, most of the comon cars can run STU (FC RX7, the list you gave, miatas, KA24-DE power 240SXs, late Z31 300ZXs). so can a lot of ITA cars that are over displaced for STL (focus RS, 240SX with KA24E, BMW E30 325e, etc...)