I Just did a 0-60 test on as level a ground as I could find. it's a little up hill actually. and it turned out 9.55 seconds?

I thought these cars were supposed to be in the 12-18 seconds. it takes a second or so, to really get moving, then it PULLS HARD and shifts solid, when I get up to 40 it really gets LOUD and then poof I am over 60 MPH. now I know the overboost is disconneted, and my transmission is JUST rebuilt, but I am suprised at the time.
I can also easily pull 85 (*as fast as my 82 Speedo goes) on the highway. I have never had any problems passing anything, and my fuel economy is pretty good.
any ideas why it's so fast?
possible speedo off? I will verify on mile markers on the highway soon. I also have GPS on the laptop, so I can see what it thinks I am doing.
John