the fmu lies to your computer to add the fuel that is needed with lower lb injectors to make them equal bigger (lb) injectors, but you are maxing out the 19lb injectors and you shouldn't use more than 85%of the injectors. The fmu has a diaphragm in it to adjust the fuel. Most people get rid of the fmu and just add 42 lb injectors because the fmu adds fuel pressure to get the fuel to the motor. If you use 30 lb injectors with the stock fmu, it will run the motor too rich. So it is cheaper just to put in 42 lb injectors and get rid of the fmu, but the car has to be tuned when you get rid of the fmu.