The speedo should be correct. At any throttle position this thing won't lock up under 50 MPH.

 

its a Stock 80E tune?

4.10s and 245/75/16 tire tune?

 

got a copy of the tune?

 

Yes, it's a stock 2004 4L80E/6.0 trans calibration. I did a segment swap on my 2004 4L60E/5.3 tune. The only change I made to it was eliminating the lockup in 2nd at WOT. Not sure why GM did this. I'm running 3.73 gears.

Yeah I can send you my tune. What's the best way? Email?