Quote Originally Posted by Blome View Post
If you want a better lower chest you just have to stimulate growth throughout the entire pectoral muscle. The shape of your pectoral muscle, however, is determined strictly by your genetic make-up. It'll grow how it's predetermined to grow not by which area you "target."
Agreed, you can not isolate your lower chest. The best way to develop it and add fullness would be to increase the size of the entire chest area. That, and a low level of body fat would show more fullness and size in the lower part of the chest.

Hope that makes sense.