Mamba

Hi guys, My Suburban 19 has been making a weird noise when I put the foot on accelerator. I was trying to record it but couldn't so I found this guy on YouTube who had the exact same issue on his Yukon. Do you guys know what noise this is ? It's coming from the floor on driver's side or within that vicinity. It doesn't make the noise initially like when I am pulling out of the garage/driveway, but as you pick up speed, there it is ! I took it to the dealer and they said they cannot hear anything... I even test drove it with them and they said ok we will check it out, later they replaced the muffler and called it quits but that noise never went away. Need some expert opinions on this on what this noise is and how to get rid of it. Any help is appreciated - Thanks