I found what I was looking for. A friendly Toyota dealer made this copy of the manual.
It shows that the Prius inlet timing is shifted over an angle of 41 degree from maximum torque to best FE.
Now it is time to make a mechanism for the Suzuki Burgman to realise this kind of inlet cam change . At 70 MPH I only use 1/4 turn on the throttle so it must be possible to do the same as the Toyota Prius.