I would also recommend getting a pipe tap and opening the hole a bit allowing your bushing to sit in further. I did this with all tapped holes on my Performer intake. In my case it was nothing more than for looks. I hate seeing a bunch of threads on a fitting, but in your case it could make it difficult to get the hose on if its sticking out further than it should.

I just took my time on each. Cut half a turn or so, and fit the part, etc, etc...