Jumpdrive,
Even on the older 72-200 with PEC you had the eec and the "notch" for the power levers, so it's not only for the -500 series.
About the 90% excactly does not really happen in real life ,I have seen anything from 100% to 112% on the -500 series during take off - especially the 42-500 had a tendency to go up to 112%.