If you wheel it in the mud think twice about the open element filter. I bought a OE filter for my 98 F-150 4.6L 4x4 and learned quickly at the car wash. I went to one of the washes that has an underbody sprayer when you drive in and as soon as it started spraying the engine started missing. I looked under the hood and the filter was soaked in water. Being a frequent off roaded, I am working on fabricating a lower side shield out of sheet metal to shround the botton half of the filter.
As for performance, I too had the K&N in the factory airbox and I did not feel a seat o' the pants improvement with the new set-up; which also included a large metal pipe instead of the factory squished plastic tube.
Depending on how the fabrication goes, I may clean the K&N and put it back in the factory set up if I can use the big pipe with it. Oh well, looks like more fabrication for that one...
.45ACP SA 1911-A1
.40SW SW Sigma VE