Headshake while exiting a turn is the result of carrying to much weight on the rear wheel (too much throttle, front wheel unloaded). The front wheel looses and regains traction repeatedly untill the weight is balanced (aproximately 40% front 60% rear) and the front suspension can accurately track the pavement again. Keeping the throttle rolled on and staying loose on the bars is the only solution in this situation. If you were to hold on to the bars tight you would transfer the front end wobble to the entire bike causing a possible slide/highside. Also a steering damper will calm down a head shake but not eliminate it.