Technically you can get away with flushing the system with 1litre (when it's rbf600 $30 a bottle, I've got 2 unopened bottles in my garage), mechanic is bit of a perfectionist which is why the 3 litres (when its cheap fluid I don't mind)
It's usually a good idea to run a oil catch can at track days. With the oil in the intake piping, i would say it's possible the oil has lubed up 2 joins and has caused a very small boost leak
I've got the GTR ones on my R32 GTR and they work a treat, they did require alittle modification with a angle grinder (check uploaded pic) but otherwise I can full lock both ways without scraping my wheels (stock 16" gtr wheels with 225's) on them. Just a word of advice when you get to fitting these, GTR's radius rod are bent straight out the factory, to accommodate the GTR wheels so don't stress over them being bent.
I've asked my mechanic that and he said it's not worth doing, should flush with the same fluid you intend to run in the system. Took 3 litres (BMW fluid $10 at trade per 500ml that has a boiling point of 302c) to completely flush my previous boiled fluid out (brake pedal to the firewall last Mallala before the course).. aprox 500ml per corner and whatever left over to fill ABS unit, lines and master cylinder resouvior. Castrol make a cheap DOT4 called Super Response (or Super DOT4 I can't remember), has a boiling point of 280c and was about $10 per 500ml at Repco last I looked.
Without a pressure regulator, the pressure will be whatever the fuel pump does at 12v (or whatever voltage they run at).. hard to say if it would run ultra rich or ultra lean, either way the fuel injector spray pattern will be off.
Note I said only at the track, all Nissan 5 speeds have the common redline 3rd to 4th crunch gear change (if shifted quickly), i believe it's a design fault with the 3rd and 4th gear.
My gearbox is in perfect nick, I put lightweight shockproof in it just because I've got some crunching at the track (and only at the track) with the previous fluid (most likely genuine nissan gearbox fluid)
Once it's boiled it's useless, but even when it hasn't been boiled, over time the lines take on water and the boiling point is lowered alot. Just get about 2l-3l of cheap fluid and flush that through before next track day, will do a better job than old brake fluid even if the existing stuff is good like Motul RBF600.
Taking the front pipe off and fixing the flex pipe whenever it breaks (which would be really rare) is much less stressful than replacing broken turbo/manifold studs and bolts and turbo gaskets with a front pipe with no flex-pipe (Trust MX comes to mind).
Sounds like problem with HICAS. As a temporary fix just pull the HICAS fuse and it shouldn't give you any problems.. usually ideal to remove HICAS completly (and whatever lines are left) as well as lockbar it down
each engine, rb20, rb25, rb26, rb30 use different CAS so I don't know if that looks right or not.. if I recall the key is part of the cam itself, might need a new exhaust cam
Might work out cheaper to get a replacement Nissan 5 Speed as I believe you can't get R32 GTR synchros anymore and the R33 GTR synchros are so different they need to be changed as a whole set (this is all from vague memory).
I managed to top out at 164km/h with my 200kw (boost set to 12psi).
My brake pedal was consistant all day, even after the 6 laps at the end of the day. I'm running RDA slotted discs up front with QFM A1RM pads and some unique autosports front brake air deflectors, nismo crossdrilled discs on the rear with genuine nissan pads and BMW dot4 fluid in the system (barely a week or 2 old), also have a Cusco brake cylinder master stopper as well.