Have you increased the rear preload to cater for the Pillion in a Million ?
If too firm, the chassis which used to absorb some vibration, then shakes through all the frame as the energy from the motor has to go somewhere. It usually gets damped by the springs and oil in the suspension.
For instance, an over firm front end puts the extra tingles into the handlebars.
Too little preload for both Rider & Pillion weight, can bottom out the dampering too, with similar unpleasant results.