So we all know that the shirts we buy have to fit our throats or else we get constricted airflow when playing our instruments (besides being uncomfortable in every day life). Working with instruments, mouthpieces, and musicians has given me insight into the overall picture more than any one element. I do believe all three are connected and when one is not in balance with the other two… life becomes more difficult.
It is important to be able to isolate issues in your playing so you can know if they are the mouthpiece, the instrument, or you physically. If the fit is not correct in the mouthpiece or instrument these issues can lead to physical issues which is also important to know and be able to diagnose. Quite often I see musicians playing huge mouthpieces because they are trying to get the air flow to be more free, open feeling as their facial muscles have become tighter as they have developed their embochure through their season. You can reach a point where you can pretty much play anything and sound good and this is the scary point where you can pick a bad piece of equipment and have it effect you later when you are not in good form. To get good air flow you do not have to always go to a larger diameter mouthpiece with more cup volume which probably has the same throat and backbore as your smaller mouthpiece. While the aperture of the face becomes larger with the larger mouthpiece, (cup diameter) and there is more cup volume, the venturi (throat) of the mouthpiece is the same size giving you the same compression point as the smaller mouthpiece you were on. This is one of the most often made mistake that I see.
Proceed with caution at this point as you could just get another mouthpiece (same as the one you are on) with a larger throat and often be content with the air flow but not mess with the balance of face/cup volume. When attempting change I never use the mouthpiece I am on currently. Leave it as a control and compare always back to it. If you change the mouthpiece you are on you will never have the “one” to compare to and only have the memory of what it was.
Muscle memory is an important aspect of playing one should consider when making changes so do not change three things and not be able to tell what did what. If the larger throat does not achieve what you are after you can then proceed to the next logical step which is, backbore, cup diameter and then last cup volume. All this being said, if the mouthpiece just has a terrible feeling rim then obviously your first step is a new mouthpiece with different style rim.
The more in tune you are with yourself, and your playing, the healthier you will become in your playing and your music. Approach change methodically and carefully and you will find yourself knowing why the new mouthpiece works for you.