I have a 6.4 BGE short block in a 2011 5.7 truck, I am absolutely not switching two sets of gears to hurt MPG and turn more RPM. It actually tows great already but a little more never hurts and selling the cats will offset a big chunk of the price (actually more than the price if I can use my craigslist headers).

I am not causing global warming, I am just trying to hold off a impending Ice Age!