I have 4800 miles on my 15 3500HD now and at about 2K I did some tuning on it to build some emissions enabled tuning for a customer who wanted more throttle response and make it a little more fun to drive so I built the tunes on mine and sent them to him. and have 2800 with the tune that I have been running and have been happy with it and it seems to regen about once every 250 miles or so up until I had the oil changed friday. as soon as I left the dealer and opened it up a little heading home I could immediately tell it had more power. also notice that now if I'm rolling through and intersection and flat foot it, it will break the tires loose even with the traction control on and running 35's and 20's with a lift. the next thing I noticed it the soot grams climbs faster now. (watching it on a CTS2) the only thing the dealer did was change engine oil and filter and washed and rotated tires. they reset the oil life as it is at 98 % I noticed shortly after leaving. is there something in the programming that would release full power after the first oil life is reset after a certain amount of miles? bout has to be cause it sure didn't run like this before.