As usually disclaimer first

I don't want to put you down or being smart ass here. I'm just getting grumpy after my crash
In my very humble opinion, if you got your first bike couple months ago you don't have to worry too much about spending money on bike upgrades.
Main thing you need to work right now is the skill of handling the motrocycle. I've did 4 trackdays last year on stock FZ6, then I've changed only fork oil, front springs, front preload, SS lines+brake pads and did another 3. This year I've used same config (just refreshing fork oil now and then) for 3 trackdays this year, changed gearing to -1 front, moved to B+ group and i still found my place around other guys. I've did 3 more trackdays and then i've MOVED DOWN to SV650S to learn different skill set and see what's about SVs everybody are talking
I've never put shock.
I think my upgrades cost me around $300-400.
All the time I was riding FZ6 I felt very comfortable. Sure, each step allowed me move forward but if I would spent $2k upfront on upgrades I wouldn't be able to afford those first 7 trackdays. I'm just looking on my pictures during those days and my riding then was really messed up

My lines were bad, body position didn't existed, I was scared to go above 100mph - no upgrades can fix that.
I would suggest investing low money on bike (SS lines, pads, fork oil, front springs), put good sport tires and spent rest on track time than any other upgrades. There is nothing else that can improve your riding (especially if you are new to track riding) than just seat time.
It will take some time until you will learn to ride faster and you will have to upgrade.
I also agree with Erci - FZ6 is very capable. You WILL have fun riding it - almost stock - at the track. But it's no match for any track oriented bike like R6, GSXR600, ZX6R or CBR600RR. But again, those bikes should come in right time

I was running loops on my FZ6 at later days around some of those new guys at R6s and GSXR600s
Just my $0.02...