The new tune is substantially cheaper if you are a previous customer. However you have to have the GDE ECU with the tune overwritten by the dealer. Mine was overwritten which is why I am getting the EPA tune (with the trans tune).
The pre EPA was wonderful. The engine ran smother and cleaner, and the milage increased. It also displayed when the particulate filter was being cleaned (burning off the particulate). The big problem was changing the GDE tuned ECM for the factory tuned ECM whenever you took the vehicle to the...
I have had the (pre EPA approved) GDE tune for quite awhile. I am now getting the EPA approved tune which leaves me with the original ECM which will be unused because of the ability to change the GDE tune back to the original tune with the flash tool.