Fuel pressure valve. Connects to the air box on a Cerbera speed six, to nowhere on all other speed six powered cars. So if is not a Cerbera pictured, you are fine. Regards, Björn.
The Cerbera SpeedSix is the one where it is not connected to anwhere. I stand corrected. The Cerbera Airbox has no connector for the valve tube. Sometimes there isn´t even a tube connected to the valve.