The 2006 Ford 6.0L had an EGR. I bought the truck and the PO had disconnected the EGR and threw it away but it really wasn't deleted. Kept getting an trouble light (the one with the crossed wrenches as memory serves). Got 10-12 MPG when I bought the truck. Did a proper EGR delete with kit and get 10-12 MPG and towing get about 10 MPG (5th wheel). Don't have DEF on a 2006 (thankfully). Judging by what others on the powerstroke.org forum get for mileage, I would say mine is typical regardless of the delete. I do have a towing tune and it is supposed to add 50 hp but mainly only effects shift points and don't really notice much, if any power increase.