I ended up buying those 21-203bf filters, but after test fitting them I decided to just clean/oil and reuse my k&n's. There is a little black bar/brace/support that is directly above the filters (at least in nismos) that has a few screws in it, and it holds some kind of wire looking thing. I took it off to better access the filters, and when the AEM dryflows were installed, due to the thickness of the bottom part of the filter, the bar would not go back on.
It is probably fine to leave that support piece off, but I didn't feel taking it off and resecuring the wire thing.
Comparison shot:
nismonster-albums-aem-dryflow-21-203bf-picture60669-comparison-shot-two.jpg
One of each installed:
nismonster-albums-aem-dryflow-21-203bf-picture60674-comparison-shot-two-filters-you-can-see-how-.jpg
both dry flows installed:
nismonster-albums-aem-dryflow-21-203bf-picture60673-they-seem-fit-fine-without-support-bar-way-b.jpg
Here you can see it coming in contact with the support bar:
nismonster-albums-aem-dryflow-21-203bf-picture60671-you-can-see-little-here-support-bar-will-not.jpg