Most such home made mufflers are to reduce noise with a minimum loss of power, an ideal way to learn a little bit about engines is to make your own muffler. It helps satisfy your curiosity also and give some a sense of satisfaction in being able to produce something useful on their own. It also allows you to adapt to special physical constraints if you are designing your own model. True, you may have little or no success but then again, many are quite good. All who tried learned something, often something useful.