I never start with small turbos, I just go straight to the niggest Stage Turbo, or Biggest N/A tune up possibe.
When I say tune, I mean race exhaust, race flywheel, triple disc plate clutch, race ship,race flywheel, port polish, engine balance and any other things like that that you can do. Basically do other stuff before you go and slap a big a__ turbo on. If you wanna know more, just ask.