I can only tell you that I had the TSB update that is supposed to reprogram the trans/eng for turbo lag and it did nothing to help. I now drive in 5th gear most of the time on even the slightest grade and have to drop even lower if I anticipate passing. The lag is terrible and I advised my wife that if it kills me by quitting in traffic, get a lawyer and sue the SOB's for not fixing this. It took a full 4-5 seconds to rev up in city traffic a couple weeks ago while changing lanes and putting the pedal to the metal. It seems related to the kickdown of the trans and getting the rpms up before power comes on. If the rpm is already built up, there is less of a problem. Of course I cannot build rpm from a stop and have to be really careful pulling out in traffic. Miserable situation and does not affect all of the trucks so there must be some program glitch. I kept my 2004.5 for this reason alone and if I don't find a solution soon, the new truck is going away. Can't live with this problem.