Daniel... Daniel..Daniel... Daniel... please PLEASE go back and READ anything in this thread I have posted.
The open element filter with "MAF-adapter" is the WORST thing you can go for your 4.0 or 4.6. PERIOD.
Keep the stock box, put in a fresh filter, do the replacement ducting from the MAF to the Throttle Body (TB)...
For the guy/gal who had issues with the "cheap plastic parts" or whatever he/she said... Wake up... the Intake on your 4.0 or 4.6 is the same basic poly-ethylene crap you are crying about... the plastic is actually a BETTER heat conductor (aka releases heat faster) than the convoluted rubber crap from OE. Thinking and research are your friend...
Bottom line kids: Getting rid of the convoluted, rubber ducting is where the MPG & HP gains can be found. a straight, smooth, consistent flow of air is what you want. The ECM will adjust for the changes. If you have exhaust and other mods, a tune will show even MORE gains in both MPG & HP.
Don't confuse yourselves... Its an internal combustion, gasoline engine. Doesn't matter if its got a 2 barrel carb or the latest/greatest EFI: AIR/FUEL in...SPARK!.. Exhaust out....
Improve all 3 efficiently, make HP & gain MPG....
Rob