OK, final answer. This now takes into account the actual AC physics files for engine torque, the rev limiter, as well as the effects of the turbo(s) if present.
Supra
1 = 6800
2 = 6800
3 = 6320
4 = 6170
5 = 6200
Skyline
1 = 8000
2 = 8000
3 = 7490
4 = 7700
5 = 7390
RX-7
1 = 8300
2 = 8300
3 = 8300
4 = 8190
Nissan 370z
1 = 7500
2 = 7500
3 = 7500
4 = 7500
5 = 7500