No Splitfires have the track record that the OEM ones do. I have new OEM in my car - been running them at 1.5 bar for three years and expect they will continue to perform since my first set lasted 15 years.
The difference between the front and rear diffs is mainly size (front being smaller). Both rarely give trouble and you should get your CVs checked first.
Don't guess. When you are on the dyno unbolt the exhaust and see if the 70kw comes back.
How much will you pay for a stroker kit? For me RB30 is better value for money.
Here's a couple of 2.8 strokers making 450 awkw on conservative street tune with stock intake manifold (one with -5s one with TO4Z):
http://www.trademe.co.nz/motors/used-cars/nissan/auction-757017549.htm
http://www.trademe.co.nz/motors/used-cars/nissan/auction-745582841.htm
Since you are in Japan a PFC or an F-Con would make sense. Did they want $1000 just to tune or to supply fit and tune a Nistune? $1000 for the lot is ok... just for the tune not. But your first tune will be more expensive anyway.
I would have thought that with higher lift cams you would have put in new or stronger valve springs. Having said that I still think you would get better results (more low down power) with stock cams. Here are my charts (you have to allow for the bigger capacity) but with stock head cams and springs:
Yep all of them
Headlights, tail lights, probably colour of cluster.
S2:
http://www.trademe.co.nz/Browse/Listing.aspx?id=711155799
S1:
http://www.trademe.co.nz/Browse/Listing.aspx?id=717748186
These are 18s off a v35 Skyline GT Coupe Sport Edition (with spacers). I believe the M35 will fit but may need bigger spacers. With 40 profile tyres they are a bigger rolling circumference than the C34 wheels but the speedo is pretty much spot on.
Seriously you need a manual conversion! Its not a matter of the auto reading lower its the real extra transmission losses resulting in less power being available at the wheels where you want it. I looked back at my old graphs from when I had an auto and they were similar to yours. My graphs now are much smoother and the boost is rock steady (G4 Link with Synapse external W/G).
Regarding the cams my understanding is that the cams you have fitted will shift the torque upwards so yes another 10kw max but less poke lower down.
VCT is normally set with one run with VCT turned off and one on to see the optimum change points.
And yes Z32 AFM will do 300 - 350 kw but not 450.
Bottom line is your car should be pretty zippy with the power you have now!
Getting a cert is easy (all my mods are certed/legal) but it costs around $550 so you tend to do it once for all the mods.
Over here the cert process is remarkably sensible.It is run by the Low Volume Vehicle Technical Association (not a government body) . Certifiers have a lot of discretion and although there is a guide manual which mandates some things much is left up to their experience and knowledge. For example they will pass Cusco camber arms but not some of the dodgy cheapo versions although there is not a list of approved arms as such.
Would have been interesting to see it with stock cams. How much power were you expecting to make? Z32 AFM won't reach to 600 hp.
Andy from X-tune is familiar with Nistune but he's quite hard to get hold of. I am pretty sure the tuner at Torque Performance does them too but having said that I'm sure it didn't take Soichi long to find his way around it.
Are you able to lock the auto in gear for tuning?
Nistune
Or for more money Link/Vipec
Just to be clear there is only "Plug" in available - whatever you use it will need a good tune before you can "play" (drive the car).