Well - good luck, Adam
Here is my experience with that stuff so far:
I been modeling and toying with cold air intake, and, unless you sticking in peltier driven cooler - no way you can make something that will be better than stock box. Pity - but true. You cant get colder air from underneath - overwise in autumn/winter/spring even on road you will get some melty snow or water in intake. And redirecting from inside of fender is plain pointless in summer - b/c air in there is bloody hot. In fact its hot in winter too, at least for my 94... Plus its already increasing length of intake, so you need some little helper to not compromize "sucking power"
But then peltier + some sort of radiator-like mesh to suck air through and cool it - isnt very effective due same issue - you need helper b/c you effectively blocking intake..
Then again - may be i am wrong - so post your design here, if you will get something
So far all designs coming up to be just something like me old air intake - cone filter with reflective barrier to protect from exhaust's heat - not very effective.
Again - could be just me. But my engine compartment is pretty bloody hot all the time in summer.
As on HP gain - allegedly you can gain up to 20 horsies by swapping to less restrictive filtering system. However same less restrictive system will (as in article i posted in that other thread) suck in hot air - so real gain is really depends on general temperature of compartment. I can say that my XTerra really got some horses back after switching to K&N FIPK kit. But Rover didnt gain much from switching to cone filter with heat shield. But then my Disco's compartment feels like oven in comparition (why spell check fails that word?) to X.