I have the same question as the OP. Looking for a streetable track tire like NT05, RE-11, Direzza Z1 for OEM 220s. Z1s don't come in 19s, NT05s and RE-11s are only available in 275/30R19 and 245/35R19, which will make understeer worse.
Are there any options other than the AD08s? Is a square 18s setup the only practical choice?