Installed the Agile Offroad Diff Breather kit. There were a couple of differences between the list of parts in the instructions and what’s in the box, but everything shown in the photos in the instructions is present.
Instructions say a 13mm deep socket can be used to fit the new breathers, but that wasn’t the case - the fitting for the hose is sufficiently wider in diameter to prevent the socket from fitting. Used a ratcheting wrench instead.
The 8mm hose retains its coiled / spring shape, making threading it through/around things a test of one’s patience. This is definitely a job to do BEFORE you fit skid plates if at all possible.
EDIT: as John says in the YouTube video, both differentials hissed as the factory breathers were removed, indicating both were holding pressure.