I’d be interested to hear if the dealership was ever able to provide any improvement or resolution to your flutter noise. Any additional details would be appreciated.
Well... my dealership has been wstill no resolution. The last time they had my car for 2weeks checking things, but GM would not allow them to fix anything because they already replaced my exhaust.
When leaving the dealership I was pretty much told “gm says it’s normal” but the service manager seems to agree with me... it should not be normal, or tolerated.
I was told I could take it to a muffler shop and have the passive exhaust valve cut out, and weld back together, or by an aftermarket exhaust to put in. I do not feel it’s my responsibility to do any of that when they will not confirm that that is causing the noise.
My Denali is going back to the dealership next week for the 4th time, but this time they are having an Engineer from GM come to the dealership to work on it. So... I will update again when I get it back...