That would take one HELL of a loose converter. I dyno'd my old car with 4 different converters in it ranging from a 2400 rpm stall converter up to 3500 rpm and none of them reached any higher speeds before hitting the fuel shutoff on the dyno than they did on the track/street.

At any rate, point being, those of you trying to argue that the vehicle will be doing a different speed at a the same rpm between being on the dyno and being on the street are trying to defy mathematically proven formulas.