Focal Length Reduction:
Speed Boosters compress the image circle projected by the lens, effectively reducing the focal length. This means the lens will appear wider, and the field of view will be broader on the smaller sensor.
Is there is something I'm not understanding correctly about what a speedbooster does?
Edit: I think I understand now. I need to use a speedbooster with a different lens, not a microfourthird, it has to be a lens for a bigger senser.