Good kill no matter what happened.
Don't want to call B.S. on your story either. But, a couple of questions. Are you sure it was a Z06 and not either a regular coupe or a 99 or 2000 FRC (the predecesor to the z06)? Regular Vettes are a bit slower than a Z06.
Again, not trying to cause a storm either. Just wanted to get all the facts. Again, you may have beat a Z06. But in looking at the stats on your car if you did, it would be that you beat the driver, not the car. That is not to say a kill isn't a kill. But, the Z06 is lighter and has more HP than a GS (even a modded one).
As for launching a Z06. In my first pass ever in the car with 1100 miles on the odometer my car ran a 2.03 60' / 12.77@ 110 leaving at just off idle (1100 rpms) and granny shifting on the first pass down the track. After a total of 9 passes in the car I had it down to 1.9 60' / 12.30's @ 113. After working on my launch technique (lets say about another 6-8 passes I had clocked off a 1.85 60' / 11.933 @ 114.52.
Z06s are not that hard to launch. Clutch slip/ clutch release is the key thing. I have cut a 1.74 60' on the stock radials. I have cut a 1.61 60' on ET Streets.
Here is the thread on my rececent 1.675 60' / 11.596@118.53 pass.
http://www.z06vette.com/forums/showthread.php?s=&threadid=30089
Again, good kill no matter what it was, or who was driving...