It's odd to me that these covers are so frequently missing. The cover does not seem to pull off very easily, so I'm assuming owners are preferring the squared look of the upper IC and removing the cover. I have in mind to manufacture a CNC'd billet cover for the Sy/Ty engine project in the shop. It's a few months out, but I'll have to post some pics when the cover is done.
I should first say that I'm still a newbie at CAD work, but here's a quick drawing of an IC cover. The thickness of the final part is 0.40". Adding the section that covers the hose inlet would more than double the thickness of the part (and cost of material).