You didn't weigh the head/head cover before and after? I was hoping to see how many grams you shaved off.
That plug is in a mighty tight spot. One thing I have noticed is that all the junk in the way has a tendency to keep my 18mm socket sort-of aligned so that I can get the thread started. But then, getting the loose plug out of the cavity can be a bit of a chore. I really need a rubber insert for my socket. A standard 18mm plug socket with an insert won't fit into my stock cavity. Have you tried a standard spark plug socket in your modified setup?