I have had this setup on my 2004. 5 now for about two months. It will not defuel when the egt reaches my preset temp (1050) after turbo. Bully Dog replaced the monitor but that didn't make any difference. Does anyone else have this setup on their truck and what is your success with getting the system to defuel as you are told it will do? My performance increase is great in the performance mode, I am not going to try it in the extreme mode because I think it would harm the auto transmission. I have lost some milage mabe 1-1/2 mpg but that may reflect the fact that I drive it harder. Lots of smoke if you sit the pedal hard but if you ease into the throttle the smoke is minimal. I am impressed with Bully Dogs support, but the place I bought it from (that I found from this site) will not even return my emails since the 30 day refund time has ran out. I would suggest that if you want to buy a bully dog product either get it from a local dealer you can talk to face to face or direct from Bully Dog.