Exactly.
Cutting scoops into the hood of an efi car just dumps dirt on the motor.
To really pull air through the radiator and past the motor, a simple cowl creates a low pressure zone above the windshield that is quite effective at drawing air through.
Everything I've read seems indicate the opposite - that aside from parked, at 5mph at above it actually creates a high pressure zone at the base of the windshield that forces air into the engine bay. This is great for a Carbed motor that intakes air at the top. Not great for cooling though because it creates more pressure in the engine bay.
Heat extractor hoods, however, do take advantage of a low pressure zone over the top of the hood and they help to bring air through the radiator. If I thought it would fit with my TFS-R box upper, I'd have one of those in a heartbeat.
At a standstill, such as in rush hour traffic, there's no way to deny that a cowl hood helps as you can see the immense amount of heat distorting the air coming out of the cowl, though..
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