Unless you have injector problems now, or have done extensive mods...no. They would be a supporting mod, at what point they become necessary I don't know. I think stock injectors are good up to about 450HP
If you consistently see injector duty cycle in the >85-90% after installing power adders then you need bigger injectors (and/or possibly an upgraded fuel pump to boot) otherwise no need to replace the stock ones. Basically adding bigger injectors on any engine will not produce more power unless you can get more air into the cylinders (i.e. improve volumetric efficiency). Adding bigger injectors to a stock motor (requires updating the fuel mass vs injector pulse width) won't deliver more fuel.