Ah! Very clever use of the different air speeds.
The leading tunnel does in fact go into the duct under the engine cover and exits at those tunnels we see in photos of the back. They could actually be radiator cooling?
The aft tunnel goes into the duct on the floor as shown. It's funny its very transverse. The two aft ducts seem to open up near the starter hole. Maybe they are using the low pressure of the starter hole to help suck the air in the coke bottle zone through it. This makes sense as the air is normally extremely slow in that area near in front the rear wheels.
Anyway. The above, has proven that my previous notions of the ducts exiting much earlier was wrong. I did not know they went so far back. But the photos have also confirmed that the 4 inch tall vertical fins work without the help of the tunnels.