I don’t like the rubber grommets because they wont last for a long time and found a better solution.
These Nylon snap bushing will last much longer, they need a hole of 3/8″ and have an internal diameter of 1/4″ and ACS has them on stock:
I inserted them with a bit of tank sealant:
Looking good after cleaning up:
I also added some tank sealant on the outside of the AN fitting:
Breather lines has a length of 22 mm:
