Twice the calipers, twice as many pistons.
Twice the fluid volume needed to move those pistons.
I guess part of this "upgrade" is to install a larger-bore master cylinder, and a more-powerful booster.
And then you need a couple more calipers up front.
But at least you got rid of that evil park brake.
The way I see it, his braking force remains largely unchanged, he just won't change rear pads before he sells the truck or dies.