Best thing to do right now would be to datalog and see what speed the PCM is seeing, it may be something other than a speed limiter or a combination of parameters causing it.

He's running a 4L80E, he has to have a DRAC/VSSB for it to function correctly. The "Output not from DRAC" is for not E transmissions.

With the steeper gears, it possible that the PCM is reading a higher speed than what you are actually running at.

The easy way to adjust for this is modify the jumpers in the DRAC module, to...