i took out the 2 screws, popped off the plastic piece, brought it inside and used a 48mm hole saw, you lose 1 of the plastic clips because it directly underneath the hole i drilled, but it still clips back on nice and tight and doesnt rattle with 1 clip missing. it really lifts the sound up higher and it sounds like the tweeters ar pointed right at your ears.
that and it was my 1st time mounting tweeters and i wanted to learn on a piece that would be easy to replace if i screwed it up
as far as mounting, they came with a W-shaped metal piece that holds them in place