About the secret menu, just hold down the start button as you're selecting your course and you'll get the extra balls/heads. Thanks for being the first to find it.
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Wow! It was that easy I wonder if you get some advantage if you
use other heads/balls. Maybe I´m wrong, but when I played with
the "operation thunder" head it felt like I had more time left on the
levels..BUT of course I could have had a good run also:)