The problem with a cat is usually after a lot of miles due to soot and oxidation loading. That was the reason DC made a cat test pipe for 2nd gens. The cat would plug up enough to restrict outflow and the cat test pipe could be installed temporarily to see if the cat was causing a loss of power.
So, I doubt anyone removing a cat from a relatively new truck would see a quantifiable difference. Down the road, literally, is where a cat can become a problem.