That's not correct. With Boost Local Enhancement turned on, you get a more powerful mode that your in, not the straight shot to the 1,500 watts. Like if your in Eco and hit Boost, you get Eco+. With this turned off, and you hit boost, then that takes you straight to the 1,500 watts. Then when the timer is done, you go back to the mode you were in.
I don't think you'll ever get to 90RPM when your in the fall flat on your face boost mode. Feels like your in ECO, now try getting 90 RPM out of that, maybe on a steep downhill.