So I just re-installed the '06 Sierra's PCM, which I just had tuned by Ryan Gick.
The test-drive was too short to check the gas mileage, since I only went about 9 miles.
But this is the best $85 investment possible.
The previous tuner left the shifting a disaster, with NO WOT up-shifts at all. And it was cruising enriched rather than in closed-loop.
Plus the part-throttle 1-2 shifting was very harsh.
All that, for $75
Well, Ryan wiped that, loaded the latest updated stock tune from GM, then adjusted everything as per my requests. Very professional, excellent customer service.
You read this a lot, but in this case it's true: This is exactly how the truck should have been built on GM's assembly line. It now drives exactly how a new one would if the 4.10:1 axle ratio was a factory option.

 

Thats a heck of a price...it costs $100 just to license a vehicle with hptuners

 

glad you're happy and not wanting to go back to a stock truck

 

Thank you.