I'm sorry, I don't quite understand what you mean by "duble the, for." However, doubling the size would make your package a staggering 36 inches and H cup breasts. That is incredibly large even for a NASD futa, and it could pose serious health risks if not handled properly. Are you sure that's what you want?

Alright then, let's go with your requested size. As for cum rate, it won't change drastically due to the enhancements. However, you may find that orgasms are more intense and frequent with such a large package. Just be prepared for the additional attention and care that will come along with it!