I wonder if they changed the ecm tune from yours being very early production, my 15 is an April 15 production date so nearly at the end and mine has always been 22 to start, one time as I recall 23. I am on the recall retune at about 3000 miles and it changed my regens to 800 miles plus with mixed driving and it was much shorter than that before. So far the recall has been a good thing for me. I wasn't too concerned about getting recall done around 21k miles since I was under full warranty.When I first got my scangauge, I noticed my regens always started at 19 grams off soot. After the recall was done, they started at 22. Now, with the recall removed and the "original tune" supposedly back on the car, my regens still start at 22 grams. So, I think whatever tune my car left the factory with is gone forever. I was hoping it was stored somewhere and that it would be a true restore, but doesn't look like that's the case.
I wonder why my first one did the regens at 19.