who's building and mapping for you? just out of curiosity - if your quite happy with running that turbo then thats the important thing, andy forrest that maps most of the imprezas round here recomends the smallest turbo for your hp aims thats all.
running in i believe is a thin oil for 50 miles, then slightly thicker for the next 950 miles, avoiding boost but not sitting at one speed or revs for any prolonged period, runs up and down the bears varying engine speed between 1500 - 3500/4000 rpm in your case at a guess. change to full fat oil at 1k then supposedly gradually increase revs in stages - ive just gone for broke after 1k and its never done any harm but that was standard engines