Southern Implosives--a myth?

[RonButters at AOL.COM]

My local phonetician/Southern dialect specialist writes:

<<I don't think there's any truth to the Southern implosive theory.
At least, I've never heard a Southern stop that sounded especially
implosive.>>

No scientist wants to say "never" without exhaustively examining the topic,
however. Does anyone have any good-quality recordings that might be used to
confirm or disconfirm the implosive hypothesis?