I have seen several posts saying that the GDE tune "shuts off" the DEF for the 2017 ecodiesel, and the DEF gauge shows the tank is half full just to make it look like it is working. I contacted GDE and they told me that DEF is still used for the 2017 model. Can someone elaborate on what was meant by DEF being shut off? I want to get my truck tuned soon, but I want to make sure I understand what to expect afterwards. Thanks!