When I tell Low / High switch I mean the one that changes throttle response map, not the one that goes for the light in the dashboard. Have you tried to put this in short? I have just come from my car and put the wires in normal position.... throttle response was delayed at least double the time that when in short. I don't know if this is the same system in the DIsco, but I think you should try it. In my case, due to bad condition of the plug, the ECU always was "thinking" I was in low range, giving me delayed throttle response during the first cm of throttle travel.
