There are some post in GiantessCity, in the 3D Illustration section, with a poser story called "Love Love Lily", created by an GREAT artist called Amoneo, with a lot of women grow (I love this comic, like a GTS/Grow fan). And in the Chapter 3, starting in the page 227, there is a futa character experimenting some like a penis growth. If you want the full story, search "Love Love Lily".
In this page start the futa character:
http://giantesscity.com/forum/viewto...9912&start=195
UNFORTUNATELY, the comic is incomplete and the artist say that is probably that he never finish them.
PD: Sorry for my bad english.