[DeTomaso] Picture comment.

[Göran Malmberg]

Air temperature is important to keep low. If the ambient tempareture is 70F and the engine compartment is 150F the outside air density will be some 7,2% greater. Since mass air flow increases in direct proportion with density, Hp with 70f air will increase at the square root of 1,15, which is 1,072 or 7,2%. 300hp will become 322 then. 
As for "Ram Air2 effect we can expect some +1,2% at 100 mph and 2,7% at 150 mph. 

The front of the roof is low pressur area while the pressure goes down at the rear to become low as it leaves the roof over the  rear hood opening. 

My own scoop provide a slightly greater pressure iside the lexan plenum than that of the engine compartment. The air is also a lot cooler, how much is different becouse of speed and trottle use. Intake temperature is easely meassured monitoring the Haltech box.
But it is not reaaly down to ambient at cruising speeds.

Goran