Yes it is your DA. Running in very low DA that you were able to set your personal best at is very lucky and deceiving at the same time. I've stressed in the past how important it is to pay attention to the DA on every pass. As you can see from Mke's post the DA changed on every pass. With enough passes and consistency on your part as a driver, i.e. similar mods, launches, tires, etc.. you will be able to predict your ET within 3 hundredths of a second. Yesterday at a local shootout I ran 12.40, 12.399, 12.393 in qualifying. Eliminations broke out with a 12.379 on a 12.39 dial, then bought back in and broke out again with a 12.367 on a 12.37 dial. The DA fluctuated from 3890' up to 4400', and my car was a half second slower than my personal best. Was I worried, not in the least. Once you have enough data on your car you will know how much .01 you will add to your personal best baseline for every 100' DA is higher than the 250'. My best was at 1400' DA and just over 2000' difference slowed mine a half second. I did use the stock conti's yesterday and soft launched, so I lost maybe a tenth. Still my Performaire PA2 was dead on with my prediction after adjusting for the tires. I'd recommend to check the weather for your next event, use a DA calculator online to get an idea of what you may run.

Sidenote: MikeR are you kidding me? Negative DA and you wasted it on an 11.96. Just send in your ECU to Washington to ummm some tuner there and get your 11.7 already.