Here's a short video of a few cars from the last dyno day I went to at Arizona Dyno Chip. Seriously a good place for confident results with a good guy running the dyno which knows what he's doing. The video represents a Ford GT as stock, but I think it had a pully. All the other cars are highly modified. We've had all these cars to the drag strip and the trap speeds come out pretty much dead on to the results. I really trust this place.
http://www.youtube.com/watch?v=mOSD9vlnRqE