Wow heatin' up.
Anyways, I was watching this vid:
Looks like the basic regulations for Tsukuba N2 race were (in the vid 6:00-ish):
- Engine must me 4A-GE(NA)
- Curb weight must be 780 kg or more
- Roll cage must be 6 pt or more. No Aluminum.
- Side bar is requirement
- Both door must be original (cannot be different material)
- Door lining must be genuine.
- Exhaust note must be 120 dB or lower.
I'm pretty sure there's more for the Original N2 Race.