I'm about to get an 09 GMC from my dad and I'm looking to lightly tune it it will be a daily driver. I've tweeked on my 13 gas burner a little with good results and I'm looking forward to the diesel tuning. I'll be doing a lot of lurking here.
So no firm shifts with the Allison? I guess that makes sense with the torque of the diesel opposed to the gas engine.Stock tcm tuning will yield the best shifts, making sure your fuel system is running 100% from the tank to exiting the injectors is key. Changing the allison have 'firm' shifts will only shorten friction life.