Piece of 4" pipe and a hose clamp will attach that 6637 filter. Only problem with those is sucking hot air from under the hood. I've had no luck finding a Ford severe duty air box upgrade for your truck.
The elusive severe duty box.
I think the K&N cold air he has is pretty good, easiest air path , if designed correct by Ford. The 6637 is a snug fit.
Motorcraft seems to be the oil filter of choice, clean fuel,full n fresh oil = happy 7.3.
I installed a Edge Insight monitor to watch vitals and a PHP Hydra chip..
The Edge Programmer is rumored as having bad effects on E40d's.
With PHP I picked 7 tunes ,25,45 and 60 HP towing tunes as well as stock,80 HP performance tune and a Hush tune that quiets it down so maybe the drive through attendant can hear you.
If you haven't figured it out yet, I Like this Truck.