Andy is the 'guru' of DSMChips.
As for what to tell Jeff at DSMChips, tell him you run base fuel pressure and what octane fuel is available to you. If you want a custom fuel map for 11.5 A/F ratio and want to run say 16 degrees of timing, you can ask him to do that too.
And no, having the T25 now won't make a difference. The chip will compensate for the bigger injectors - It doesn't matter if you want a T25 or a 50trim.