Great work, mate. You'll often find that your trap speed will be up as a direct result of a buggered launch. i.e. Your best ET and TS will rarely be on the same run.
In saying that, a 12.6 isn't out of the question with some new tyres. Those Nittos have sure seen some serious work in their lifetime and have almost certainly gone off.
Very good effort and a perfect example of why a private track hire is such a good thing to be part of.
Adrian
P.S. I hope you didn't fall over in the car-park afterwards....