If you have a custom tune already, you also may need them to take out the spark adder table for the EGR in the tune.
Yes thats right...having the EGR allows you to run more part throttle timing. So you will loose a bit of part throttle power and milage by reducing the timing.
I was going to remove mine....but after reading into it, I decided not to. I dont want to give up any power. (NOTE: Removing the EGR does NOT effect WOT, as the EGR shuts off automatically when you romp on it.)