Every diesel I've ever owned I've had to turn off in a drive through. 6.9, both 7.3l, 6.0l and 6.7l. Every one of them quieter than a 4bt in an eb though lol.I have an 06 duramax LBZ, I have to turn it off if I use the drive through to make an order, and I have stock exhaust. But it sounds great.