Adjustable FPRs were more popular before EFI tuning was common and easily accessible, and they're still used today when really trying to push injectors to their limit. But the Z32's ECU (and virtually every tune for the Z32 out there) is built around the assumption that the fuel pressure is always going to be 43.4psi in relation to the manifold pressure. So unless you're doing a totally custom tune, for the car to run right, you would need to set it at 43.4psi anyway. Which is exactly what a stock one does. So unless you have an extraordinarily demanding application, it's there's really no point.
