i assume these will only run with the stock electronics and abs system, only asking as ill need a controller for my mk2 golf haldex car, I'm hoping not to have to fit the ABS from the S3, but i can fit 4x wheel speed sensors if that helps in any way
I should preface this by saying I have done almost no research and everything below is based on assumption, but you might want to speak to HPA as this is potentially an extremely flexible piece of kit.
My understanding of these units is that they intercept the data coming from the rest of the car before it reaches the Haldex controller. In doing so they can manipulate the controller's normal behaviour, for example, by making it think you're at WOT all the time.
If that is the case, there may be little to stop the HPA unit inventing all kinds of data for you, preventing the need for ABS or any other electronics the controller normally expects to be present.