if it MUST be understood, then why didn't you explain it? pressure waves, convergent cones, divergent cones........ who cares, unless you are building pipes or are a tech freak. as long as you know what longer and shorter cause, then it's all good. the info given here is good, and all you REALLY need to tune a pipe. you may have to try a few different pipes to find what works for your setup, driving style, and boat. two "identical" boat/motor combos may not like the same pipe, in the hands of different drivers. just another excuse to go burn more nitro!