Drill a hole into Fuel Filler Neck?

Well, when I did mine, I used grease on the drill bit, ran a vacuum while I drilled, and placed my brass barb inside the trunk, just above the trunk surface. I used epoxy seal all, and have had no leaks, smells or issues since. My filler neck has an inner sleeve of some sort, so I used the drill just enough to cut the outer metal. No issues with my FCC either since.

Ken