Folks with the stock airbox, I just changed the original air filter and the replacment motorcraft filter was completely different than the original filter. The original had an orange rubber surround and a sort of yellow paper filter material. The whole filter is very stiff and the paper was pleated length wise. The new filter is black rubber with white paper, pleated width wise. The new rubber is also much more flexible, as is the entire filter. I could be wrong but this new filter looks like it will flow a little better than the original. The new filter looks like a Wix or Purolator design to me.

While I was in there, I checked for oil in the airbox, around the MAF, tube and throttle body. I saw what might be an oil stain in the tube near the throttle body, but nothing more than that. I did not see any large amounts of oil in there. The throttle body itself looked very clean, with no dirty, oily residue visible from the outside. Sometime, I'll probably take it all apart for closer inspection, but from what I see now, it looks like I don't need a breather at this point.

2k Red L, 4000 miles