First time here and I'm really hoping you can help because I'm a little bit lost due to my situation. I'm new to 6L80 tuning but not to cars, in fact I own a repair shop. While rebuilding the engine in one of my personal vehicles (2003 Yukon XL2500) I decided I sure would really enjoy getting a lower first gear ratio instead of the super tall first that the 4L80E has. So I ended up swapping in a used 6L80 from (I believe) a 2011 Tahoe. I used a TCM2650 from PCS to control the transmission while maintaining my facory 2004 PCM to control the engine. It's in the car and works through all the gears but now I need to tune it and I'm not sure where to start. It seems like a huge part of tuning the 6L80 is working with the engine TM, unfortunately there's no such thing with this setup. All it has from the engine is the TPS and RPM signal, other than that the TCM2650 has one table called a Main Torque Map and is just an estimation of your engines power at different RPMs and throttle amounts.
Before installing the transmission I did open it up and inspect it and it looked pretty healthy, I also installed a Trango SK 6L80 kit, Transgo CS-TCC kit, and a CTSV converter.
Where should I start with this setup?
Thanks,
Jacob