I don't think this would have happened in sport mode as the motor does react much more quickly.
The difference is only throttle mapping, not engine mapping. (If you had DSG it would make another difference, but not with manual.)
A stomp to the buffers gives you the same power in any mode - ok, for the duration of pushing the pedal it doesn't but once you are at the end of the travel, its exactly the same.
I don't think on a motorway drag race its going to amount to a whole load of difference. Its more about a more gradual throttle curve for fuel economy.