Hi Nero,
NSI-189 would boost the stimulant effect of every chemical I have tried it together, but at the same will mellow them, taking the edges off. It makes many chemicals to feel better.
I had a recent discussion with another member, that has very good results adding NSI-189 to adderall, lowering adderall by one third with a better effect overall.
If your current combo really works for you (with no many side effects) you can just try adding a small NSI-189 dose to see if it will improve.
NSI-189 could boost mood and increase energy among other positives, but also give anxiety (dose related) to some. Alternatively you could try using a regular NSI-189 dose and if you get anxiety try to add a small Escitalopram dose or tianeptine sulfate.
NSI-189 can boost the effects of methylphenidate, and make it better (according to my experience) but could not replace it. If you need it for concentration, NSI-189 alone probably would not be enough, although if motivation is the real problem could help (especially if you add noopept or PRL-8-53).