"High impedance injectors usually range from 12-16 ohms. Low impedance injectors usually range from 2-4 ohms. High impedance injectors use a saturated switch-type driver. They open a little slower and the current stays more constant once the coil is saturated. Low impedance injector drivers (peak and hold) allow more current to flow to open the injector faster, and ramp it down to hold it open. "