From what i've found so far, not a lot without major alterations to engine components. The fuel pump won't go much further. I can't find an induction kit, not even a K&N filter. I have now turned my attention to suspension and brakes, the Koni FSDs have made a big improvement, still exploring whats available for brakes.
What chip do you have by the way? Have you had it dynoed - Turbochip claimed 210, dyno says 196.