[cotharyus]

I just put one in my 04.5 - Generally speaking, a K&N drop in is the first thing I do when I pick up any vehicle - depending on the application, I've seen anywhere from .5 to 2 mpg increase with just a drop in. Additionally, K&N claims an 8 hp gain using that part number over the stock filter. For the record, I've not yet driven a full tank of fuel through my truck yet, and didn't have any numbers on the stock filter, but my confidence in the product is such that I feel I can live with whatever the results are.