birt since you spoil the "undisclosed" bits, here's my contribution:
For interest's sake, the HKS turbo kit on the vehicle costs about 380,000 yen ($5,700) to buy in Japan, not including fitting. The TEIN suspension about $4,000 to $5,000. The HKS exhaust around the $2,000 mark as a rough guess. Intercooler about $2,000. Twin plate clutch somewhere between $2,000 and $4,000. Injectors x 6 = $1,600. Airpod $300. Each of the additional gauges is worth $200 to $300. The computer I'm not sure on, but certainly not cheap.
That's at least $18,000 worth of aftermarket extras, not including the Nismo 300 km/h speedo, computer, and the factory LSD, or fitting of the parts. It wouldn't be surprising to find that the owner had spent close to $30,000 on the car once everything was totalled including fitting the parts plus additional items that we are unaware of.