As with any engine...when things "break in" they loosen up and rotating mass ect isn't working so hard to rotate....It is possible you feel more as it wears in...To be expected which is a good thing!!!
I think the rumor was the ecu had been per programmed to be slightly down on power during the first ten hour breaking period. Following that the ecu would automatically revert to normal programming which would provide full power. Question is, is that rumor or fact? I wouldn't know since most of the trails I rode the first ten hours I didn't push it hard. Wanted to break it in moderately. Only floored it for the first time at 11 hours to see if it was holding rpm during shift. I think only the people who ride dunes regularly or race would notice any difference if there were any change.