I will try to clock mine on my way to work tomorrow. GM says 8.1 seconds. I never put it to the floor so it we be interesting. My Stock Yukon xl with the 5.3L feels like I am driving a school bus. But, I do not expect much out of it. Last time I had it weighed it came in at 5800 lbs. I think that it would be around 15 seconds with drag slicks on it and the third row out! Maybe I should just post my speed in knots.