I don't mean uncontrolable, but it's not as stiff as I remember them being. It's been a while since I hit any real speed. (which is by NO MEANS what some people consider fast here) Now the last time I was on some pretty shaddy tires (very flat spotted rear), would that cause it to get shakey, it wasn't just up front either ? I'm scrubbing in new tires now.
IMO
1) First attack your suspension settings.
https://www.hayabusa.org/forums/?act=ST;f=47;t=30985;hl=suspension
A speed shop will charge you about $50 to do it for you.
2) Do the damper mod if you can't afford the aftermarket damper right now.
https://www.hayabusa.org/forums/?act=ST;f=6;t=75640;hl=damper Great improvement but not a GPR. I constantly switch mine on the fly depending on the road condition/speed.
3) Make sure your front and rear tires are same OEM. Make sure they are balanced.
4) If you weight more than 190 lbs... might want to invest in new springs if aggressive in the twisties. This is more of a "feel" factor but great investment for me (245 lbs).