My intense tune sucked. My overkill PCM is much better and is probably the best IMO.. In the same scenario, same gas, same weather same temps my overkill PCM cut my kr in half. I would usually see 5-6* kr with stock PCM now I barely see more than 2* ever. If I do see more its usually crap 91 gas that causes it, as we only have one station here with 93.
So to answer your question. Yes a canned tune PCM will help performance and reduce kr, but will not kill it all. I don't think will ( overkill ) touches the maf tables unless you have him tune for a cam, I/c, or other major mod. Fuel tables are left untouched as well I believe.