A Your goal is a wise one, and the quest for the best solution isn't easy. An exit vent behind the radiator can improve cooling if it's designed so air actually comes out of the vent at speed. Your main concern should probably be under-hood heat from that hot turbo which, presumably, has no heat shielding on it. Here are a few things you should think about:
1: NACA ducts, like the one on the Evo X, are for letting air into the engine bay. The new Evo's turbo is on the back of the engine, and the vent blows air onto the turbo much like the vent on an SRT-4 does. Your turbo is in the front, and there's no room for a NACA duct ahead of your turbo.
2: At speed, the air at the rear of the hood tends to be at relatively high pressure, since it's hitting the windshield and getting forced up over the roof. Lifting the back of the hood to let air out, like the riceboys in those other magazines, is more likely to actually let air in.
3: Getting cooling air across your radiator and intercooler means making sure the air pressure in front of the car is higher than the pressure in the engine bay. If you open the engine bay to the pressurized air at the back of the hood, you'll likely increase the pressure in the engine bay and reduce cooling airflow across your radiator (the Evo X and SRT-4 were clearly designed to deal with their relatively small turbo-cooling vents).
4: An Evo IX-style hood vent, behind the radiator and above the turbo, can serve double duty of improving airflow across the radiator at speed, and letting turbo heat escape when you're stationary. Ideally, the vent should have a small lip at the leading edge to create a low-pressure area over the vent that encourages air to leave the engine bay.
5: I'm too lazy and too much of a carbon snob to have anything but a stock hood. Some day, when I find a properly vented hood made of real, vacuum-bagged, autoclaved dry carbon, I'll want one. But then it will be too expensive and I'll just drill a hole in my hood instead.
In case you missed it, #4 was your answer.