2018 Sierra 6.2 Exhaust Help

[miningaway]

Hello everyone, I currently have the GM Borla Performance Exhaust on my 2018 6.2L and I want more sound. The guys at muffler shops recommended I replace the muffler with this one: https://www.holley.com/products/exhaust/mufflers/street_chambered_mufflers/40_series_original/parts/430402 Part number:430402. I am aware that my current system has a flapper which eliminates drone but would that carry over to this louder muffler?

[3tspapat]

The flapper is in the pipe before the muffler. Unless you also change that pipe, there's no reason why it would be gone.  Just note that while the flapper helps reduce the chop/drone when in V4, it doesn't help much with drone from a loud muffler when not in V4. Also the muffler is only 13". I think the GMPP Borla is much larger. They will need to add some piping for it to work. Just make sure they don't weld anything to the GMPP exhaust.