I legitimately am not understanding why you're wanting to modify a program that is giving great results. Are you anticipating that the modifications you want to make will give you even greater results?
It may just be me and how I approach things. I don't give much credit to theory, only results. A method is only as sound as it's success dictates, and no matter how much science backs something up, if it doesn't work for you, it's worthless.
It appears, based on the results you are getting, you do not need to extra volume. At best, modifying the program will allow you to continue getting great results. At worst, it will give you not as good results. Changing a working method to pursue a potentially NOT working method does not seem like a sound idea.