Only one: HFC, Gen3 Intake, or CBE?

Scribe

Semtex, you can disagree all you want, but the fact of the matter is that changing the tune first will yield good gains. In addition, much of the gains in power from the aftermarket intakes isn't from additional airflow, the stockers flow just fine, it is actually from changing the MAF signal to read less air is flowing and thus leans out the charge to a more ideal ratio. Those disputed tests where the guys at 370z.com held the air-fuel ratio at stock levels proved that the power gained from additional flow was minimal. This points to where the intakes make most of their real power, which is changing the reading and thus the combustion mixture, not from additional airflow. If you were to take a stock 370z and flash it, you will see good gains.

And as further proof, this has been done and tested at 370zdotcom.

Had they gone with a better map, their gains would have been greater.