Cephalotus pitchers as a general rule grow to a maximum size of about 4.5cm. However there are claimed to be 'Giant' forms with pitchers that grow to around 8cm. These are named the 'Hummers Giant' and the 'German Giant'.
I am currently growing both of these clones - see pictures right.
I have also managed to get a regular Cephalotus to produce individual pitchers of a similar size to the ones shown - but not as a general rule.
Physical differences comparing 'Giants' with regular plants - I find the 'Giants' have thicker/coarser looking peristomes as well as more wrinkled chunkier looking pichers in general.

For further information on this subject - CLICK HERE - for an in-depth article by Agustin Franco, which I think covers the subject very well.