MakerBot Print is our newest print-prepration software, which supports native CAD files and STL assemblies,
allows you to interact with all your printers via the Cloud, and many other exciting new features.
I took a look at your new nozzle, and while I didn't copy your changes exactly, I have made similar changes to mine. I can also optionally add the fins. I uploaded an STL of just the lower section of the duct including the fins for you to take a look at.
I am going to change the bottoms of the mounts, as they look like they could cause problems printing it, and mine are much cruder than yours, then I am going to print out versions both with and without fins, and compare them