According to wikipedia the E6300 is just an E6320 with half (2MB) of L2 Cache disabled, is it some how possible to enable this? http://en.wikipedia.org/wiki/Core_2_duo
I have not heard of it done either. Even if you could do it you couldn't tell any difference except in in software testing.
Yeah I wish we could do it though, I'm sure it would have SOME effect in real world usage. Then again also I wish we could unlock pipelines on the 7600 GT(I know there aren't any to unlock so don't go crazy lol).
As far as I know, although the extra cache does exist, it's disabled in such a way that you can't re-enable it.