A brass-wind musical instrument mouthpiece comprises: a cup comprising a rim and an inner rounded surface in communication with a bore in communication with a counter bore in communication with a backbore. An alternate embodiment comprises: a first portion comprising a cup in communication with a bore in communication with a counter bore and a first coupling portion; a second portion comprising a backbore and a second coupling portion; wherein the coupling portions are coupled together. A brass-wind musical instrument mouthpiece kit comprises: a plurality of first portions comprising first portions, in a variety of shapes and sizes, comprising a cup in communication with a bore in communication with a counter bore and a first coupling portion; a plurality of second portions, in a variety of shapes and sizes, comprising a backbore and a second coupling portion; and wherein any first portion may be coupled to any second portion.