-injector controller (AEM) - optional, an injector driver is only needed "if" you use Peak & Hold injectors and "if" you want the quicker opening aspect that comes with them, otherwise you can use resistors to get the ohms in range for the ECU and sacrifice the quicker opening time. Also, there are some Saturated type top-feeds up to 750cc/min, no controller or resistor is needed with these.