Just got back from running the tattletale test. Removed the rear hood seal. Taped two pieces of twine (some fluorescent pink stuff I had hanging around, the stuff you see used on construction sites to hold a spirit level) to the back edge of the hood where the creases in the hood are and another to the wiper arm (centerline of car). Up to about 30-35 mph, they didn't move at all. Above that, they indicated that some air was going into the engine compartment.

But that may have just been turbulence. I parked and turned the A/C on to turn the radiator fan on. Engine was well warmed up (170F oil temp) but I could feel no heat coming from the rear of the hood. On inspection, I found the gap between the hood and the engine compartment is very small.

My conclusion is that removing the seal doesn't accomplish much, if anything. Off to put the seal back on.
Edit: the fasteners for the seal are not evenly spaced, so it's all but impossible to install it wrong.

So it stands to reason that if we opened that gap up somehow we would be making matters worse as far as airflow is concerned? Thanks for actually testing it, too much of this is theory.

Looks like it. :(

I'm rather surprised the the radiator fans wouldn't push at least a little bit of air out when parked. Where is the air going?

It would be interesting to see a similar test run with the undertray vented. But I'm not gonna hang my head out the door and look under the car while going 60 mph. :)

Has anyone looking into a very high static pressure fan setup yet? I know the GTM fans are better but does anyone have static pressure data on stock vs gtm?

Man, I just loathe to give GTM any more of my money.

What happened with GTM?

They're a forum sponsor. Not worth getting into. PM me if you're really interested but it's probably nothing you haven't heard before.

Unless there is somewhere for the air to go, upping the pressure from the fan won't do much good. It sounds to me that the engine compartment is pretty well sealed (not totally or the engine would overheat all the time).

Where does the air vent from the engine compartment? I just made a look around the engine compartment and underneath and didn't see any vents. They've got to be there somewhere. It might help to enlarge them.

I'd assume that the air exits underneath the car behind the undertray. There's really nowhere else it could go, right?

Yeah that has been my assessment, that it gets pulled out under the car.

Achieved... thanks to Aero Jacket:

If I end up with a vented hood, that's the one.

Sounds reasonable to me. I'll jack the car up later and take a closer look.

The vent closest to the windshield works great. The other one doesn't do much. Another drawback is weight. With the reinforcements put in place the hood is several pounds heavier than the stock hood. I could care less, though. It's functional and easy on the eyes.

That was a wild-*** guess, so I may be completely wrong. It just seems like the only place that air can go.