I have a basic understanding of how each parameter affects the system, but that understanding is strictly limited to an "all other parameters unchanged" scenario, which is fine in theory but not really possible in practice. I use Matt Frost for mpc mods. He knows his business. Typically I tell him what I am running into and ask him what he recommends be done to adjust. Usually its a combination of throat and backbore, but not just one. I once asked about a particular backbore mod and if it would suit my needs. He recommended something else, so I went with it. It works far better than I expected. Moral of the story: Even if I understand what is written in the Conn booklet or in Jeff Parke's essay, I will never know as much as the empirical knowledge of an experienced mpc maker.