Wait a sec dude!
The Jetta has a full engine belly pan (and side skirts). The engine is not open to the ground like that. I believe the flow exits out the back of the bay under the firewall, though its been a while since I've been under there and I have a diesel geek skidplate anyway.
Furthermore anyone with a Jetta might as well block off nearly the entire lower grill and especially the whole top grill. Actually one interesting note here is that I did my grill blocks sequentially, and the lower block made a huge difference on warm-up time, while the upper grill block appeared to do little if anything. I've probably got about 20% lower frontal flow area into the engine bay vs stock. I started with my lower block like this but trimmed a tiny slot open on the bottom during 90 deg summer days. Wish I hadn't now, as I need to remake the full block for better winter warm ups.
But I suppose this doesn't matter
as much for flow towards the rear of the car. As long as we get that hood flow figured out.....?
I appreciate your continued efforts! I really like the improved flow detail and vectors, too.