Mostly good advice on this thread but some bad or costly advice as well.
You have a near stock R33 GTR and you are taking out to track days. Same thing I had, same thing I did. I'm still buying more stuff for the car after it blew the turbos.
The don'ts unless you want to risk big expenses
1. Increase boost - You have a 10+yo car with known badly designed turbo's. Push the boost up and the turbo's may last ages or they could blow up first track day (mine did). 14PSI is NOT safe on a race track
2. New fuel pump & injectors - Utter waste unless you are upping boost past 18PSI on a stock motor and thats 260-270 rwkw
HICAS removal is a good idea if you have driven rear wheel drive cars fast and expect the cars rear end to behave like a normal rwd car under very hard cornering. Don't be affraid to be different and try keeping the HICAS in and see how it drives before trying it without HICAS.
The items that I have or am going to do, prices indicative
1. Remote Oil cooler I recomend one with a thermastat if you live somewhere when it goes to sub 0's in winter. $ 1500 installed
2. Suspension, go the whole hog SK does a nice cheap kit for $2500 and install can cost up to $1000
3. New turbo's, those old one will die, HKS GT-SS for the track, they allow up to 300rwkw and are true bolt on replacement items Allow $5000 with install
4. Good brake pads, there's a whole thread on them somewhere, I have EBC yellow's that work very well on the road as well but are rated for the track, though a lot of track people will bag the EBC for track work. With the stock pads I had to pull out of my last drive day due to a severe lack of pads after only 2 sessions.
5. If your disks are worn then replace with slotted rotors, DON'T go the cross drilled ones for track work. I've also been told that you need heat treated ones for regular track work.
6. OIL Management, there's lots of threads about extended sumps, baffled sumps, oil pumps, oil catch cans etc. Need to take the engine out to do a proper job. This is probably the most important items for a GTR and can be the most costly.
7. Spitfore coil pack is a great idea.
Then go the next steps of a new CPU, upping boost, AFM's, Boost controlers etc.
SK - Sidney kid is probably one of the better sources of information on oil control and track racing, have a look for his responses.