I will give you a different recommendation than most others, albeit what docjohn said in the second post should have been the end. So please take the following in the spirit that it is offered, helping you as a novice with your first HPDE/HPDS.
Here is my assessment. While understandably you are eager to prep your car and yourself for the first track event, you are running way way too much ahead of yourself and where you need to be mentally. In fact, in my humble opinion, and given that I instruct since 2000, and run classroom sessions/debriefs, you would be on my "watch" list at the track
:wink:
Your stock NSX would have been plenty enough for your first track event - if not first season of some 6-10 track events! Stock pads and OEM fluid are fine - though fresh or better pads and higher boiling point brake fluid would help. But then again, you are presumably doing your first track event in Fall/Winter right? And street tires would be definitely a plus in those conditions and for the first season or two.
As for head room, that is indeed the critical condition. Forget about harness bars and belts for now, yes they help but you are not there yet and there is ample discussion on the pros cons on Prime (do a search) ...... your instructor will not let you get to over 6/10th of the car's limit if you are novice and if he/she is in control - at least not in the programs that we run - and especially not if you are coming with a CTSC and the above posts :biggrin:
Try taking the bottom seat cushion off for more head room. It will give you at least 2" more clearance and your hip will fit more tight - put a towel on the bottom if you like a warmer feeling than aluminum :wink: Laying the back and bringing the seat forward will give you a bit more head room as well. For a first timer, rent a helmet; use a head cover in case you are worried who may have used it before. Keep it simple.
If you like your first track experience - and a lot has to do on your attitude going in (ie willing to learn rather than prove something or test the equipment), your instructor, the track program you attend ......... and want to come back again for that adrenaline fix :tongue: THEN and only THEN ....... think of the essentials as noted above.
The focus of any reputable HPDE/HPDS for first time novice students is NOT speed, but often breaking street driving habits, teachnig smoothness, predictability, and consistency of inputs (braking, turning in, apexing, tracking out) as well as track courtesy as one learns the lines. Only after some assurances of the above will your instructor allow you to add more speed. ASt the speeds you will be running, you will be surprised at the number of mistakes/adjustments that you will need to make as a first timer ...... imagine what those mistakes will be with speed!!
For a novice, as others have said, all the mods will actually hamper your learning curve because you will not know what/how each one of those mods contributes to your car's handling given your driving inputs and the particular track. Just because others say something helped them doesn't mean that it will work for you equally well - we use such information as a reference and we each tune the car based on all the other givens. Your learning curve of car dynamics will increase dramatically as you learn the effect of each change as you progress. Heck, even one hole change in the adjustable sway bars or a 1 psi change in a tire becomes a significant change in advanced driving conditions - not to mention your mental focus.
HTH. YMMV.