Update:
As any of you who have read through this thread know, I have had quite a lot of opposition from quite a few knowledgeable folks in regard to my plans to design (or rather redesign) an upper plenum for my 35. Well, I'm no fool and as Kat Williams says "if everybody in yo life says you smokin' crack, mutha%$&ka you are
probably smokin crack!". That's not a direct quote but you get the idea. Anyway, I've decided to heed some of this advice and put my plenum project on the back burner for the time being and continue my research. I've been reading a lot about the subject lately from any source I can find, and have learned a great deal about the intricacies of engine design. My plenum design has changed several times since the last model I showed you guys and it will probably change again before I show you another. Suffice it to say the next iteration will be astonishing... Well, maybe not astonishing but a little better at least.

That brings me to the rest of my imaginary intake system, which is how I keep myself busy between work, marriage, and "study sessions". This includes a revised air box, intake tube, and filter location. At this point my strategy has been to create the different options I come up with, and use my very limited range of equipment to conduct rudimentary comparisons. When I narrow the field to a few promising contenders, I'll try some more sophisticated comparative methods. Currently, I think what I'm doing is sufficient to weed out the bad apples. I've modeled a couple different intake tube ideas and run them on the "virtual flow bench", used a vacuum gauge on the intake manifold to compare resistance, performed about 15 pedal dance ECU resets, and logged some hard miles on my butt-dyno.

The picture I posted above is the most recent and I think my favorite filter location thus far. I got the idea from poking around under the hood of my Audi, in which the air box sits directly atop the inner fender liner. A common mod for increased air flow in that circumstance is to drill holes through the bottom of the air box and down through the fender liner, effectively opening the air box to the outside world directly. The picture is showing the fitment test in which the filter is just hanging from a wire. It's mounted now and in a slightly different place. Here's a newer pic:

Possibilities for this location include a fairly simple heat shield, air scoops from the skid plate and from the opening below the grill, full isolation, a larger filter, adding venting to the fender liner, or any combination thereof.
Oh yeah, and I have a new addition to the "which mods do you regret" thread that I'm sure you will find entertaining... Hopefully I'll get to posting that tonight.
Comments? Questions? Suggestions? This process has "hardened my skin" a bit so to speak so good or bad, bring it on.
nice, do you plan on sealing off this area?
The tentative plan is to finish up the piping tomorrow and see how it goes. So far I can tell that this area has three major benefits over the existing, and one drawback. The benefits are that a significantly larger (in diameter and length) filter will fit here, it's much more conducive to isolation if I decide to go that route, and it's quite a bit further from the heat source. The drawback (aside from turbo's observation below) is that the intake tract is gaining two extra bends and about 14" of length. I am dealing with that by slightly increasing the internal diameter of the excess intake piping.
that location has been tested in the past by others I think & it seemed to have less airflow than up top, measured power loss on the dyno acording to those who tried I think. it will work great though if you open up a nice size scoop to that area, otherwise it'll have less white air than even where it is now. even taking the fog light out would only help so much but would be a start, you;d need to pressurize that cavity while enclosing it to make any kind of possitive improvement. my air filters will go similar to that left & right but ducts will have to be built in too
That's disappointing. I couldn't find anything about anyone routing their filter there in an FX... Do you happen to remember any details? Maybe a keyword or something I could search for to find that thread (if it's a thread)? I suppose worst case scenario is I move it back up to the top. So far I've performed no irreversible work, aside from a slight trimming of my Stillen air box but that doesn't really affect anything but the fit.