I'd say best investment beside seat time and tires is gonna be lines and pads.
That's definitely on my list. I think braking is the next system I want to improve. I'm pretty happy with the factory brakes but I'd like something grabbier so I can get down to using 1 finger.
What kind of budget you got?
Suspension upgrades can be pricey but they honestly make a world of difference.
I'd love to do some suspension sometime soon, and have it set up professionally, but for now I don't feel like I'm exceeding what the stock setup can handle, and I can't afford it atm. I'll definitely keep it in mind though.
Full disclosure, I hate anything vortex. A lot of riders like them because they support club racing/racers, more than woodcraft. I don't like them because their quality control is pretty bad. I've seen sprockets from them with huge burrs the size of my fingernail.
Anyways, I'd suggest going with JT steel sprockets over anything aluminum. Aluminum is overpriced for sprockets. You'll never say "man, I'm glad I got those aluminum sprockets because I am now 0.0001 seconds faster per lap".
I've always used vortex or JT depending on the bike. This Yamaha I've used almost exclusively vortex, and I've been pretty happy. I'll keep that in mind though, I'll keep a better eye on the QC. I use JT in my dirtbikes and my ninja has JT sprockets and chain right now. If I start having issues I can trace back to the vortex I will go with JT.
Make sure you check all the specifics for your race org:
Most don't like engine ice and will require something like waterwetter.
Check all the components that need to be drilled/wired and pulled off a stock bike.
I'd definitely recommend the ECU Flash(Best bang for buck). Plus it drops the 1 pound of exup cables lol.
I'd get stainless lines and a more aggressive brake pads. Don't forget to scuff up the rotors to remove any glassing and attempt a cross hatch on em. You can use a rotor hone or some brillo pads.
I'd then worry about crashables (windscreen, pegs, rearsets, clip ons or oem bars, levers etc). With our bike being so plentiful there are often times numerous similar bikes so spares are a plenty but it'll suck if your day is ruined cause of a broken clip or peg. Make sure you pick whatever you would get the easiest support. For instance I run all woodcraft cause well they are in the next state over and one of the most popular. I'm not gonna get a graves or attack or whatever stuff cause its less likely others will have it.
Most importantly is tire choice and the proper PSI's and time to warm up is clear for your racing condition that day. Its super important.
Other than that is seat time, where you actively trying to address something and not doing laps for the sake of doing laps. You're better off trying to improve braking markers, technique, reference points ( at the third crack theres a little bump if I'm a foot of the line).
Our league allows engine ice, and I've been really happy with the performance so far. Come next swap I'll look into water wetter, seems to be the favorite. Braking is probably what I will start with based on everyone's recommendations. As for seat time, I've been riding track days with coaches for almost 2 years now, so I've been pretty focused on technique. I want to actually start racing now and here they have a licensing school that includes mock racing and mock starts so I can get some practice in. Like I said, my goal is to get into an actual race this year, but that's not concrete at all. If I can't keep up, I'll probably hold off. I've had help from some local shops (DTR performance and Adrenaline performance if you've heard of them) for setting my tires and passing tech etc.. as they are usually out at most track day/race days.
Buy a good set of tire warmers, I use Capit tire warmers and love them. If you go cheap on tire warmers, you could have cold tearing issues on your race tires, and they are not cheap, so don't do it.
Next buy a good rear shock, Penske or Ohlins, see what your local suspension tuner prefers to tune. A good rear shock will not only give you confidence on corner exit and bumps, if setup properly will extend the life of the tire. Then I would buy either AK20's or Penske fork internals, you can get away with a fork refresh with the right spring for your weight. But the Ak20's or Ohlins will give you a planted feel and more confidence to push in the corners.
Next I would also recommend getting a reliable quick shifter, it will make life easier and help prevent shifting mistakes later in a race when your worn out and possibly being lazy on the bike. So I would focus on the braking, suspension and shifting parts, long before I looked into any of the go fast parts. It's all about going deeper into the corner on the brakes and accelerating and getting a good drive out of the corners. And don't worry about results, just focus on learning race craft, you do that and the results will come with time.
And lastly, have FUN!!!!
I have decent warmers, at least, they get the rubber up to temp (as checked with a ir thermometer). I run GP-As or Q3s depending on which I can find cheaper take-offs of. I haven't run non-dot tires yet but I think my warmers should handle them. I'd LOVE to do a suspension build, just don't have the cash yet, and I don't feel like I'm exceeding the stock setup. Sounds like brakes are next on the list.
Thanks for the recommendations guys. Huge help. Sounds like braking and suspension next, then maybe some speed parts.