So this is an N/A ehgine with a turbo put on it, are you still using the turbo or na injectors, if your using na then i would certainly upgrade to atleast turbo injectors, what ecu are you using na or turbo, either one will not run all that well as the engine is under a completely different set of circumstances that it was designed for, i would park the car untill you had money for a tune, use the bigger injectors, pfc and get a z32 as well, the fpr is an option but really an fpr is mainly used to get a little bit more flow from injectors when they start to run out of steam, this shouldnt happen if you have chosen the right size injectors.