Hello anyone reading this, I have a 2016 C7.5 Audi S6 with about 103k miles on it, Just changed Plugs and coils, and when I bought the car originally I didn't hear this sound I'd say maybe since December of last year this sound has been persistent. The car is normal from 1st to 2nd and once I get to third I'll hear a slow build up of the hiss, once I shift to 4th its almost like you hear air escaping and the car hesitates (SEE VIDEO). Any gear past 1st or 2nd even slightly stepping back on throttle they'll be a slight lag and then it'll start to pick up speed again. Once in a while I'll also get a check engine and a "p0175 bank 2 running rich". I'm not sure if it's a vacuum leak, the PCV getting ready to fail, maybe even the diverter valves I've searched up and down the forums and I've had little to no luck finding someone else with this problem. If I could get some type of help It would mean a lot. Thanks. https://youtube.com/shorts/I_RqZffh_...1MPtA_kCr6yUY8