^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
What Dave said.
But I'll add this a good tuner will be able to work the VVT table to leave the cam Advanced longer than "stock so that should make up for any loss in low end grunt.
as for MPG, in My 2014 1500(4x2) when I had the stock MDS cam in the SRT392 Short block I was getting about 18MPG if I drove it like a respectable person. same as the 5.7 stocker that was in the truck org....but I am carrying around less weight then a 2500 4x4