What exactly is this that comes with the HRC Stg IV kit? I am curious as how it works. I'm assuming the kit comes with a FMU what ratio I'm not sure. Normally, the ratio is fit to work with the size injectors intended for use. I am not used to non-mass air cars so that is why I am wondering how this works. Is it comparable to say having a custom programmed chip/ECU? I am looking for some more info on how the whole computer functions is relation to fuel/timing and other functions. Any help is appreciated. Thanks.

'00 Harley-Davidson F150
'88 Mustang GT
'93 Mustang LX 5.0
'00 Focus (beater)

You say HRC fuel contol module help with a stage IV set-up? Actually, the DFI comes with stage IV, you must have meant stage III