My friend Kurt Muehlbacher was kind enough to share this info with me just now.
There is a Subaru hose that can be used for the vent from the crankcase to the airbox plenum. Honda part # 15763-422-000 These are getting scarce as NOS, and proportionately expensive.
Stock Honda part shown here for reference:
The Subaru part # is 11815AB143
Available for a cool $25 from your FLSubaru dealer, MSRP.
https://parts.subaru.com/p/Subaru__/Hos ... AB143.html
Our friend Terry Schmitt also identified a nice Suzuki part:
A Facebook group member referred to the German CBX club reproducing this, but that did not include any info about how to obtain it.tevan wrote: Sat Nov 05, 2022 11:43 am Here is a Suzuki number.. it is thin walled like the Honda one. Just cut a little off of it and it works great. # 13853 38300
The suburu one is thicker walled but will work as well.
And our friend Cary Knapton also has reproductions of this part, that optionally includes the slightly special clips that can be grasped from afar. Cary is a newish vendor in the CBX community, and has focused on reproducing quite a few NLA items for the CBX - his website is 100% worth a visit and a bookmark, he has some real gems for sale:
www.thesupersportshed.com