Hung:

You could try theses sites.

www.epiclust.com - they have a pe section under the story archive.

www.overflowingbra.com - A be site, but has a mpg category (male penis growth).

www.mcstories.com - a mc stie, but has a gr category (growth) which has some pe related sites.

www.musclegrowth.org - muscle growth forum with a story section. The stories are mostly with a gay orientation.