Although I'm not a Cummins owner at this time I'm in a similar situation. For the most part I hate the way that the way autos function most of the time. I'm looking at picking up a manual to help get less parasitic drag and hopefully have a little better mileage and the fun of jamming gears big rig style. Finally the Cummins trucks all have 3.42 axles so (IMO) the auto doesn't feel near as powerful as it should even though it has a decent first gear (3.23). The first gear on the manual is significantly lower (5:94) and is going to feel like you can pull the devil outta hell even with 190lb ft. less torque.
Partial De-Badge (doors and tailgate) Challenger Badges, Iron Cross HD Steps, Sterling Equipment Rollbar with 5 HIDs
My SLT may be gone, but it's not forgotten!