In my opinion, some of you are looking at it the wrong way. Others are closer.

Too much air under the hood.

Instead of helping the air get out you need to limit how much is getting in.
You want a low pressure area in the engine compartment. Doing that will force the air through the cooling package.

Run your next high speed event with the hood scoop taped off. Your engine will draw hot under hood air but you will likely see the radiator temps drop. That's a cheap test that only costs a few strips of duct tape.

Any air coming in contact with the core support and cooling package needs to be handled. The air is stacking up and looking for somewhere to go. You can add paneling/baffles behind the grille to direct air into the cooling package. If so, make it narrower at the entrance than it is at the radiator. Air is more likely to be "trapped" and not spill out over the sides. This helps create a higher pressure area in front of the radiator.
A seal between the core support and hood would eliminate flow up there. I wouldn't hurt to add an under cover extending from the air dam to the back of the engine compartment.

Raising the back of the hood and doing other things to help air get out is essentially treating the symptoms, not the problem.

Air flow is often thought of as fluid movement. Use fluid. Put the car in high speed trim and block off the back side of the radiator. Grab your garden hose and spray the front of the car. The water will go where the air goes. Block off anything that allows the water to get to the engine compartment. Doing that will find your areas of concern. The scoop will be a big culprit. Check the air moving over the top of the bumper too.