wow, lot's of great testing. your traps are unbelievable. Just a note the other non-turbo cars at the track are effected much more by the DA so they would see greater advantage with it lowered.
Here's the stock timing map according to Cobb... shouldn't get any higher than this. Really depends on what load the tune is telling the ECU. Try some 3rd gear pulls starting at low rpms with healthy shot of meth / conservative boost and timing should max. There's always some funny business at the shift with MT and maybe AT also that lower timing. But your timing does seem a little low for Meth right after the shift.