Glengemen
Husqvarna
AA Class
I had the head shake issue on mine and finally figured out it would go away if I loaded the rear or just sat on the back seat. Try that for the shake. My final answer was a stabilizer, and glad I did.The head shake problem improved but didn't completely go away when I changed tires from D606's to K60RR/TK80FRT. The only other think that might affect it is the barkbusters I have installed. I haven't worried about it much because I don't have afreeway anywhere near where I live or travel.
As far as power agree it is pretty good in the 5-7.5k range. I've had it up past 100mph several times, it will do it although I find the motor likes about 80.