the XD's are super slow in stock form. probably contributed to why they ended the 5.0. I wanted one, but it couldnt get out of it's own way. I'm sure his tuned one feels fantastic compared to stock though.8.4 doesn't seem bad for a large diesel powered truck. i have never owned a diesel but they always seemed slow when taking off from the light as stock trucks
my 6.7 will hit 80 before i merge on the freeway as a reference.