The issue on these engines isn't flow, it's filtration capability at the rated flow. The mopar (rebranded fleetguard) or fleetguard filters flow enough air AND filter to a low enough micron level to keep the turbo happy and the engine supplied. It's been dyno proven numerous times to support 550 rwhp before it starts becoming a restriction - and there's no telling if that was on fresh or dirty filters. So I'd say unless you're shooting for 600+, stick with the stock box and fleetguard filter.
If you are aiming north of six bills, based on the research I've done (way more than should be reasonable) S&B is the only one that uses a filter which flows better AND filters almost as well as the stocker. That's the only aftermarket box and filter I'd consider putting on my own truck. Banks, Airaid, BHAFs, etc flow more but don't filter as well.
K&N flows like crazy. But it also doesn't filter for crap. Sure it catches bugs and bricks, but it allows stuff to pass thru which is large enough to significantly contribute to wear on your compressor blades. My two cents is stay away from any oiled element on an engine that burns oil. Used to have one on my 06. 10k after installing it (first service interval) I could feel very minor pitting on the leading edges of the compressor blades. Replaced it with a fleetguard dry element (stock) and the pitting never got worse. Blades were perfect prior, so it was definitely letting wear particles past. Was a crushing revelation, because I've used K&N filters on literally every gasser I've ever owned... but the 06 was my first turbo and first diesel.
Hope that helps...