Are there any good "trick" carbs?

[Doug Schriefer]

Some years ago a tech at Braswell told me that the
Cup guys would test multiple carbs of the same
configuration because there would be enough
hp/driveability variation to make such effort
worthwhile(which I know in Cup doesn't have to
be very much). The guys on this board with Cup
connections can confirm or deny the accuracy of
this (old) hearsay.

At this point pretty much every cup engine program has their own in-house carburetor developement program as well.