It could be, I'm not skyline educated enough to be able to tell you, I know it has had some serious work done on it, whether by Nissan, or Nismo, or the Jap dude that owned it, I don't know. I do know:
Full lock diff
G Max Nismo clutch
Tein coil over height and ride adjustable
Super advan wheels 255/245 yokohama advan tyres
hks pod filter
blitz fmic
hks evc
blitz turbo timer
apexi turbo gauge
Greddy gauges x4 oil pressure, water temp, oil temp, exhaust temp
cusco rear wing
oil cooler
m/c brake stop bracket
3 1/2 exhuast hks viper 5" s/s muffler
cusco front top bar on suspension
MP3 player
300kph nismo speedo
different front bar
carbra
momo wheel
razo gearknob and accelerator pedal
project U brakes
And I'm told its, a bigger turbo [i haven't seen a std one, so looks no diff to me]
bigger injectors
aftermarket ECU, no markings that I could see, so don't know what sort
I also know it does 250kph with the a/c on [forgot to turn it off] an not flat, still accelerating [i have a witness to this], reckon it would be flat at 260/270kph, maybe my speedo is out of calibration, I don't know, I had it serviced and calibration checked by Olympic instruments in Pymble prior to installation, so wouldn't think so, but wheel diameter etc may change the ratio. This was at 16 psi boost, which apparently it has been built to take [or so I'm told] etc etc [i normally run at 0.75/1.2 kg/m on the evc.
i've had it dyno'd twice now, and its making about 195rwkw [189 and 197 at two seperate places, ie not the same garage].
I take all the pride of ownership etc, but take NO credit for all this, I didn't do anything. I've only owned it since May 2003.
Hope this didn't bore you too much, i hate this sort of thing a bit.
I'll get some pics out soon.