The EFI module is a SpeedPro (or FelPro, or FP Performance, or now, F.A.S.T.!) unit that can be ordered with several options. This one is configured to batch fire the injectors which fires half the injectors every engine revolution. Sequential would fire each injector seperate and timed to each cylinder. Batch fire is cheaper, doesn't need a cam trigger, and makes just as much power as sequential, but it doesn't have individual cylinder adjustment and the off idle and part throttle (cruise) won't be as "crisp".