6.2 Backfire 1 to 2 and 2 to 3 shift

[2014KL]

My 2014 Sierra 6.2 has 36k on it.   Occasionally when I floor it going from the 1 to 2 shift and 2 to 3 it will make a backfiring noise and puffs a little dark smoke.  Has anyone else heard of this issue or have any idea what would cause it?   It's weird because it seems to come and go.   It's stock tune with an airaid intake and gm Borla exhaust.   I didn't notice it was doing it until I put the exhaust on.  I've been considering a black bear tune and thinking that may help if it's a tune issue .

[XSKIER]

It's the torque management retarding timing between shifts to save the trans. Nothing to worry about, just keep the bitch floored!

[2014KL]

I figured it was something to do with that.   Seems like it loads up fuel in between shifts.   I guess it's time for a tune.  My last couple have been diablew tuned but I'm going BBP on this one.