Guys, I am a twatwaffle

Personally I blame poor lighting conditions, my butterfingers and Suzuki build quality.
So when I looked into the airbox again (i.e. at the airfilter), I saw the long part of the snorkel coming through into the airbox.
This looked exactly like the snorkel in the picture (which the guy was actually holding upside down

). Now the old brain finally clicked and I began pushing up from the inside and finally there was some movement and the snorkel assembly popped out to reveal the 3x3 hole
That thing was seated so well that from the top on could see no descernable seam.
Anyway, I can now go ahead and order the jetting kit. If the DRZ already pulls so nicely in restricted form, I can only guess how it will pull once unrestricted