I bought a cooler to do the enclosure trick I used to do with my S9. When I close it, the S19 promptly overheats.
3300w vs 1300w, the little air that was getting through those ducts was enough for the s9 but not for the new beast.
As the other said, either a boost fan or connect the fans to the ducting, although I doubt it will work for a long circuit.
I'm intrigued a bit about that picture, where does that duct lead to, I assume it gets cool air from the window and then blows it ..where?
Do you plan on using it as a heat source in winter? Either way, the best improvement would be to short the whole circuit a lot unless you plan on using some extra fans, and extra noise.
Probably a small blower is best.
I wonder if a grow tent kit would do the job, those things would be the easiest to latch on that setup.