Hopefully Kirk will respond. He's the man when it comes to this kind of stuff.
I'll help with what little I can. I ordered RaceTech springs for my bodyweight (I think mine were the 1.10) and valve kit for the front. Had a local dealer install it. I had them adjust the adjust the sag front and back for my weight. The rear didn't really need any more than that. The front springs for my weight (235ish unsuited) made adjusting preload unnecessary. For brakes, I used Galfer pads, changed to steel braided lines and pazzo shorty levers. All of the above cured some problems I'd had at trackdays. One problem was that I was bottoming out my front suspension in tight turns, making the bike wallow underneath me. I also was having to brake earlier to get that mass of bike and me slowed down to an acceptable turn in speed. Now I can run later into the turns and carry a bit more speed, without the front suspension bottoming out. I also had to add rearsets (Gilles in my case) to raise my size 12 feet up a couple of inches as, I was going through toe sliders on my boots at an unacceptable rate (3 pairs in one trackday).
I also raised the bike an inch in the rear (turned out to be more like 1 1/2 inches). This also aided in resolving the toe dragging issue, seems to have helped the bike turn in easier, and pretty much eliminates the dragging of hard parts. Well, that combined with changing the exhaust to HMF dual high mounts, as I'd lightly drug my cans a couple of times. Helps get rid of unwanted weight and ups the horsepower too.
For tires, I've got Pilot Powers on mine (not the 2CT yet, as I had a couple of sets of the originals laying around that I got on sale), and they also will make the bike dive in to the turns quicker than the stockers, due to the shape. They stick well, even on a wet track during a rainstorm (knee down in the rain? OK!). I would probably go with the 2CT type now but, the originals have worked great for me so far.
As far as the steering damper, well, the stocker works just dandy. No need to change oil or buy a new one unless you just want to. If you're riding with minimal pressure on the bars like you should be, headshake on a Hayabusa isn't an issue.
You've probably already seen this section of the site but here it is anyway just in case. Lots of good stuff here.Lastly, the most important "mod" in my opinion is one that has to do with you. Attend a good track school (the good ones are pricey, but worth every penny, I recommend
this one), and then start participating in a few track days a year, always seeking to improve. This alone will do the most for you being able to keep up with your buddies on their lighter bikes. In fact, if they've not gone to school and/or the track, likely they'll be working to keep up with
you. No kidding.
Hope this helps.
