It is important to approach nitrous as you would any other forced induction application. You are introducing a greater amount oxygen available for combustion which means you need to increase fuel delivery accordingly to avoid running lean, and as we all know, running lean can lead to major engine problems such as excessive combustion temperatures and detonation.

You can increase fuel delivery two ways. By increasing the pressure of the fuel system via a regulator or by installing larger injectors. There are also some concerns regarding the performance of the fuel pump, but in most applications the stock pump is more than capable of delivering the required pressure and flow.

It is important to remember that the required pressure is going to be proportional to the square of the flow required. So pressure will increase dramatically faster than flow will. For dramatic increases in pressure, the reliability and proper performance of pump and injectors comes into question. Increase pressure means increase power demand by the pump and injector solenoids to open the injectors, which requires an increase in current, and heat generated by these devices. And heat is one of the biggest reliability concerns when it comes to electronics. There is also the possbility of leakage through the injectors or seal failure. As a secondary concern, the extra heat generated by the pump and injectors also heats the fuel; adversely affecting charge density and power just as air temperature does.

I would suggest getting larger injectors that can provide the required fuel flow at or near stock fuel pressure. An adjustable fuel regulator may be necessary if you can't find anything that should operate properly near stock fuel pressure, and it allows for some fine tuning

Items such as a fuel rail, larger fuel filter, and improved plumbing primarily reduce the pressure drop over the fuel system and even delivery to the injectors. The primary advantage being less power required by the pump and cooler fuel. A new fuel pump is only necessary for large increases in power, or simply to have a pump that operates more efficiently at the fuel system parameters, once again resulting in cooler fuel

Hope this helps