While on this subject, 2 days ago my Cummins started the " Darth Vader" sound (low growl, lot's of back pressure, almost like the exhaust brake is engaged at idle?). The turbo lag is very noticeable and acceleration is sad at best until the turbo spools up. This is not typical of how this truck normally runs. I drive the truck probably 80% highway, just made a round trip to Kansas 10 days ago and drove from Dallas to Houston today. The odd sound and turbo lag are still there. No CELS or lights on the dash. If this is regeneration why would it last this long?