EGR valve on HDI engine and fuel consumption.

I have seen many references to this valve, and the fact that if disabled, can improve fuel consumption considerably. Does anyone know if this is also true on the HDI (in my case a 110 in a

307SW), or does the computer get its knickers in a twist? At todays fuel prices it is worth looking at any way to reduce consumption. Also, although the EGR system is supposed to reduce pollution, I doubt if it does better rhan a 10% reduction in fuel used per mile, and thus a similar reduction in exhaust emmissions. Brian.