Nitrous Oxide is an oxidizer. The only way it works is when you add enough fuel to support combustion. In a Dry Manifold kit like a Zex Kit (not a fan), it gets the additional fuel by increasing the fuel pressure causing the injectors to spray more fuel. In a wet manifold system like our Pro Fogger systems we build, the fuel comes from an additional fuel jet in the nozzles. All of this extra fuel has to come from somewhere. A larger volume fuel pump can supply this fuel volume. Without it, the pressures will fall off and the engine will run lean and bad things happen.