I decided today to take a good look at the hypertech map that comes in their tuning package for the 2003 4.3l. I had an extra 2003 S10 4.3l PCM so I downloaded the stock map from it then I uploaded the hypertech premium tuning into the PCM and downloaded that map from it then I did a compare. After looking at the map it was kind of disappointing the only thing they change is the timing table no change to fuel tables at all. For the price you pay for the hypertech programmer you would think you would get a little more than that. I know it offers top speed change and transmission and tire size and gear ratio adjustment but still the engine programming is the main reason most people buy hypertech . See picture for spark versus RPM map difference between stock and the hypertech.