I had the GM Performance Exhaust installed

[Joseph Garcia]

I was able to drive some more today while running errands, and you're spot on. With the radio off and paying attention, I can hear the DFM kick in under 55 or so, and I know it's the DFM because I hit L9 on the shifter (which deactivates DFM) and it went away immediately. And then over 65 the exhaust note becomes more apparent again, didn't matter if it was in L9 or not, but when going over 75 it became less noticeable again. So my observations match yours, the frequency or resonance of the engine and exhaust between 65-75 is when any drone is most audible. I didn't think it was obnoxiously loud, but I haven't road tripped for hours yet either.

In a perfect world we would've gotten active exhaust where we can turn it off and on via the Sport setting on the dash like some GMs, but alas they decided not to offer active exhaust on these SUVs. I'm just going to chalk it up as a necessary compromise at this point, because it sounds great running around town, I love the sound when accelerating, and it has a great rumble at idle, but the tradeoff is apparently some resonance between 65-75.

Easy fix. When cruising between 65 and 75, turn up your audio system volume.

I have a major drone on my exhaust system (I knew it would be there before I installed it, but I already knew the easy fix), and when I turn up my audio system volume, the drone disappears.

 

[Sean Michael]

As @swathdiver stated above, the sound will change as the muffler breaks in and receives its initial coat of exhaust microparticles. Then, you will hear the fully developed sound. Take a video of the noise at that time, post it to YouTube or similar posting site, and provide a link to this thread, so that everyone can hear the new sound.

When exhaust breaks in does it usually break in louder, or quiet down, or just change tone? I'm on day 3 with this new GMPP exhaust and I can't tell if it sounds a little louder or I'm just giving it more gas more often because I love hearing it.

 

[Marky Dissod]

When exhaust breaks in does it usually break in louder, or quiet down, or just change tone?
I'm on day 3 with this new GMPP exhaust and I can't tell if it sounds a little louder or I'm just giving it more gas more often because I love hearing it.

How it changes tone depends on how the particulates are distributed when they settle.
All sorts of resonance and cancellation waves are bouncing around in there ...

 

[iamlegion]

I forgot to add some context for anyone else that reads my perspective. I also disabled my ANC (aftermarket JL subwoofer and amp) so I may hear different tones than others.

One day I want to install a toggle that reconnects the ANC mic and turns the amp off.

 

[Sean Michael]

On my original post I mention that GM claims the GMPP exhaust "Helps increase power by up to 11 HP and 6 lb.-ft of torque" and "30% backpressure reduction at 300-g/s, based on correlated flow testing" (those qoutes are directly cut & paste from their website). I was sincere that it was a secondary consideration of mine, but is it believable that I think the truck does indeed feel a little peppier? I have realistic expectations, and I'm familiar with the placebo effect, but I can't shake the feeling it does actually feel a bit quicker. It's subtle, and maybe I'm just enjoying the skinny pedal more now that I can hear my 6.2L better, but that's my thought.