exhaust popping issue
 

I have a 2017 silverado lt 5.3l with 84000 on it. Upgrades i have done is a volant cold air intake, diablosport predator platinum tune and i put a magnaflow muffler on it and removed the exhaust flapper. I have been getting a backfire/popping in the exhaust. I have checked my fuel trims with my tuner and they do not run that high. I did the reset by removing the ecm fuse and also removing the battery cables i do smell a little exhaust once in awhile. Could i possibly have an exhaust leak at one of the flanges causing it. I am only hearing the backfire/popping underneath the vehicle. The vehicle does with and without the tune on it.