stand outside the truck and have someone step on it, its loud, trust me, I don't think mines that loud on the inside but when someone else drives it, it's wayyyyy louder, no where near stock volume levels

 

Yes it's louder than stock but not annoying loud. Have heard mine drive off with a 32 foot cattle trailer loaded.

 

Wow. Physics bro. Straight pipe anything and it's gonna be a lot louder.

 

Yes genius it's gonna be louder. But my duramax is no where near as loud as my Cummins were. Had straight pipe on my 97 and 5 inch stacks on my 05 and it drove me insane when I hauled cattle. I can hardly hear my duramax when the windows are up and the ac is on.

 

yes the VGT makes a big difference at highway speeds, mine does not drone at all, it is very quiet until i get into the throttle, then it gets LOUD, you can hear an LLY/LBZ/LMM from a mile away when they get into it, that scream/growl they make is very distinct and loud as hell