It took me a while to notice this thread, which I thought might be about breasts of the small "bug bites" type, but it touches on a fundamental challenge that a BE plot faces when confronting any sort of realism -- namely, relatively quick growth, especially of one area of the body, is more often pathological, due to an infection or an internal injury, than anything else. Cancer is an extreme example of tissue that grows fast, and of course certain worms can go wild. Your average gigantitis is a disease of some sort. Having lots of GOOD extra tissue takes either a lot of time -- as any believer in fenugreek may tell you -- or a little innovative science fiction. Implants, of course, are already inorganic and bypass this altogether.