Humming/whining 2020 Trd sport

I have 2020 sport that lifted 3” and I put in KN cold air and Borla exhaust. I have a humming at ~30mph and ~55mph. It only happens when barely giving any pedal (almost a coast). It sounds like from rear or driveline. Took it to dealer since under 36k miles and they told me it’s the cold air intake. I am not buying it but said if you bring back with stock air intake and still does can look deeper into it. Any thoughts? It is a Canadian truck for first 20k miles.

 

There are a lot threads about rear differential whine. Not many of them come to much of a resolution other it is normal, but I think a few do. Use your favorite internet search engine.

 

Sounds like you have the dreaded aftermarket exhaust drone.