Originally Posted by Julesandtrish
..... I must say that every time the ERG comes on to burn the NOX gasses while I'm driving the exhaust sounds much more noticeably louder.....
OK, just so you won't feel all alone. But this won't answer your question. Honestly I have never experienced/noticed anything with respect to the quoted item above. How would I even know this was happening? I have close to 10K miles on the odometer. Once in a while it gets a bit noisy when I have come back home and parked it in the garage and turned off the engine.