16kw difference? lets say 5kw could be any of the common variables that affect power on any given day..you're looking at a 11kw difference, this could be the difference in 1 or 2 degrees timing at wide open throttle.
the default Powerfc accelerate injector settings can richen up mixtures alot when you press the go pedal, they may have only been tuning wide open throttle? IMO full range torque is better than top end power any day of the week...especially on the street.