always best to work with what you have. Less is more. Plus there is just simpler ways to get more fuel without complicating things. first obviusly from tuning, then from fuel pressure and or boost reference fuel. then injectors.

Adding another injector isn't to smart as your only real option is to spray the Y pipe the the manifolds. not exactly a percise way to fuel all 6 chambers with the same amount of fuel. Id would be like tossing on a wet shot and turning the bottle off.