The control unit has a remote sensor. Tap into the vac line as normal, and connect that to the sensor that sits in your engine bay (well, that's where I've put it in my car, makes more sense). Then run the data wire from the sensor to the Control Unit II in the car.
The Defi Blue Racers don't require a Control Unit, but I believe the sensor operates in the same way.
thanks:thumbsup: