I did a log of my 1999 Sierra to get an idea of what I need to adjust using HPTuners, prior to changing anything on the OE tune. Very interesting to say the least. The OE BIN file needs some serious attention to get it to perform decently, man what was GM thinking? Here are a couple of screen shots of the AF, LTFT and Advance table histograms from my morning commute. Not very good IMHO. I will be dynoing very soon to get a baseline, then I will try an work some 'magic' and redyno it to see the results. I may track test it as well, just for the heck of it.

Air Fuel Table Histogram


Advance Table Histogram


LTFT Table Histogram