i want to get the best fuel mileage i can in my 2012 2500 hd and was thinking about deletes and a programer i would have to get the efi live programmer as all the others I'm told do not support the dpf delete my question is how much of a difference (if any) do the egr and dpf deletes make as opposed to a dpf back exhaust and say like an edge programmer I'm not really concerned with the cost (the deletes and the efi are pretty pricey) but i only want to do it once and get the best results any info would be helpful as this is my first diesel I'm not real familiar with all this yet thanks