Stock exhaust back pressure normal or no

[Dersch]

If you guys follow me you'll know ive had a slue of issues with my 2020 trailboss LT 5.3L. So the most recent which i havent really posted about is my exhaust leaks. Ive had it repaired 2 times now (one new catalytic convertor and then another replaced some clamps). Previously they rebuild my transmission and then I developed these leaks. They fix them and then a week later the leak is back. To me it sounds like back pressure (and the dealer said thats all it is and is normal). If youve ever let a truck idle for a long time and the water ends up in the pipes and goes blub blub thats what it sounds like when i give it a little throttle then let off. 

 

The dealer says its normal... but theyve repaired it two other times so i guess i don't understand why they wont now. Been waiting 3 days for a shop foreman to call me back and hasnt. Everytime i call they just tell me theyll definitely call me in the morning. 

 

So is this normal? Does your 5.3 have back pressure (in park. Rev up maybe 1k rpm, let off and i hear the blub blub every time)

 

Note- never heard this noise till AFTER they rebuilt tranny

[Phantom 4D]

Just saw this while cruising through. Did you ever get it worked out??