I know the felling. Just finished my first tank of fuel(14.5mpg). I had to show the friends what 660lb/ft felt like. Under WOT it felt like the clutch was slipping then the RPMs would drop and then it would catch. I thought it was the tires breaking loose but the truck stayed straight.
I am glad to hear that this is "normal".
Side note...this truck is fricken awsome!!
I am taking the boat to the lake this weekend. Can't wait to see what the D-max/Allison will do through the hills.