Wait. You've been running a bigger turbo and haven't done a tune? I just wanted to make sure. Anyway, you're kind of going the right direction, although I would say go with the plan to tune it for whatever modifications are done. A downpipe is another part on the list that you'll want. Really, I would go in this order:
Downpipe, larger injectors (not necessarily STi injectors, but I'll be selling mine soon if you're set on them), fuel pump, and tune at the same time.
I would recommend against doing any part separately aside from the tune. You can do that via an AccessPort or a local tuner if you have one you can trust. And when I say that, I mean the only one you can do without the others is the tune. You shouldn't do any of those parts individually without the tune. Read up on this forum and you will see plenty of people that are doing their work in the right order. Tuning is a big part of making power with a Subaru.