hmm ya not too many us sites that ive found where the people actually know what they are talking about...
the sensors would be your maf sensor or your map sensor, but if there are bigger injectors on there chances are you should find some stock RB25 injectors and put them in, i bet that would solve the problem... or at least help somewhat...
but to get some more advice on this come on over to
GTRCanada.com lots of helpful people on there, and while it is mostly a skyline site, you have an RB motor so where else would you go for good advice
just ask for help in the general tech section and im sure a few of the guru's will diagnose your problem