This is really a complex subject and it would be hard to document it all in a thread...especially with generality of your prompt.
Go check out Theo Wanne's mouthpiece museum. Read the study comparing vintage Meyers and new production Meyers. Join MojoBari's Yahoo Mouthpiece group. Google everything you can. Then come back and ask specific questions. It's a great subject to learn about but there's a LOT to learn.
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