2015 6.7L is loud and poor fuel mileage

I have owned 4 Powerstrokes..

1999 7.3
2002 7.3 4x4
2012 6.7 4x4
and now a 2015 6.7 4x4

2015 6.7 has more midrange and top end power than the 2012 6.7 by my seat of the pants, but the low end SNAP of the 2012 doesn't exist in the 2020.

I noticed the the economy was lower than I expected. I also noticed that the regen is very frequent compared to the 2012, which is why the fuel mileage is lower since it is burning more fuel...

The one thing that drives me effing nuts is how loud this truck is.. At idle it is very quiet, but once the truck warms up, the engine gets very loud under acceleration. Much, much louder than my 2012. I have had 2 friends drive my 2015 and they both agreed it was on the verge of being obnoxiously loud. Here's the kicker... it is smooth and quiet when the truck is first cranked after sitting overnight or for a few hours. But once the truck warms up a bit, you can hear the rattle kick in under acceleration like a switch is turned on. It is not a gradual noise increase, it is an obvious change in the programming like there is a bad sensor or something. Its like the timing is advanced way too much. Another question that bother me is how to increase fuel mileage on 6.7 powerstroke?

Any thoughts?