the fuel adjuster is like an SAFC, although it has a lot more load points, meaning it can be tuned very well (although it will take much longer to tune = $$)
In regards to who can tune it, i havent looked into that yet, I think Dr.Drift can tune them?
Max boost on stock r33 turbo is debatable, plenty of threads on sau. I think the limit is about 10-12psi?