I went 5/64" 2.0mm with mine. Provided the BE clones are drilled to the same spec(which could be hit or miss) it should work but leaves very little material at the top. Try 1/16" 1.6mm, I first did that and it opened it up enough I would have been satisfied.
Check for burrs also, had a few where the center and air hole opening meet, removing those opened it up a little and removed any whistle it had.
Can I see a picture of the material on top?
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