Many times manufacturers will deliberatly "detune" an engine with software, just so they can later notch it back up a little at a time for marketing reasons. Other times just having more time to work on an idea will allow them to sneak in an extra horse here and there w/o any major( or even physical ie; software) changes. GM did this quite noticeably with the northstar engine, partially to avoid the unspoken rule that nobody gets more horsepower than the Corvette.