2018 A8. In manual mode in 3rd gear throttle up right above 3000rpm. I’d say 3300rpm and let off the gas, as it drops right to 3000rpms it’ll start gurgling and popping. Gas it back around 3300 rpms and let off the gas and gurgle and pops again. I can do this over and over and then when I downshift to 2nd gear is when a very loud POP backfire happens every time. All stock except Borla X pipe and Katech PTB. Thought I’d share.