Pbrad074

I tried putting it in L9 and it worked…..chirp is gone!!! thank you!!!!

Thanks for the update - And pardon my ignorance, but what is L9?

Thanks for the update - I guess the muffler replacement won’t help me then…. I will keep looking. My truck will also chirp coming to a stop when the trans down shifts from 2nd to 1st. Are you able to reproduce the chirp at low rev up, 800-900rpm in park?

Update: With much negotiation, I’m bringing the truck back to the dealer this week to have the muffler replaced. I will report back once installed.

Hi All, I’m new here and I love all the information in the forums. I recently purchased a new 2021 Denali with 6.2L that had factory installed cat back exhaust installed. I noticed a loud chirping noise on cold start-up, while in park with low revs 1000-1100 rpm and then goes away and finally when coming to a stop when the transmission second to first gear. I have brought it to the dealer and they can’t figure out what the noise is and have taken the exhaust apart reinstalled with new gaskets and the chirp is still there. I don’t know if it is a back pressure issue or the performance exhaust itself. I have attached a picture of the tag on the muffler to see if anyone knows who manufactures the exhaust system (borla or corsa) and if anyone has experience the same chirping noise. thanks in advance. Peter