Not sure which 1999 GMC Sierra Performance Chips & Programmers are right for you? We have over 7429 customer reviews, with an average rating of 4.5, to help you find exactly what you're looking for. Here's what some of our customers have said:
"I installed the Max Energy on my 99 Sierra 1500 5.3l. My truck has 35" tires and a 4 inch lift, dual exhaust, and cold air intake. I was previously getting about 11mpg hwy. After installing the regular fuel tuning, which took about 5 minutes, I have averaged 14mpg hwy, so I picked up 2.5-3 mpg. So I am very satisfied with my purchase in that respect.
I have also noticed a gain in power. With cruise on it doens't need to kick into overdrive as often as before when driving into the wind.
The one dissapointment that I have is that AutoAnything advertises that tire size can be adjusted up to 54 inches. This is incorrect. It only allows adjustments for tires up to 34 inches (confirmed by a Hypertech tech). So I was unable to properly calibrate my speedo for the 35's. Otherwise I am very happy with my purchase." —Jon O from Cottonwood, MN bought a Hypertech Max Energy Programmer for a 1999 GMC Sierra, 5.3L V8.