Here's a new question for you, in that it's not asking if my mouthpiece is too shallow, but too deep! I've been playing on a Schilke 20 (what I've affectionately dubbed the "toilet bowl" ) for roughly 3 and a half years now. I made the switch from a 7C after playing Euphonium for a year and borrowing the same mouthpiece from a friend. It feels pretty comfortable to me. However, a few months ago I tried out a friend's Schilke 14 for a few days, and besides the obvious change in tone color I feel like my range improved slightly, and it just felt amazing. However, I don't have anywhere where I'm currently located where I can just go and try out trumpet mouthpieces, unfortunately, (and my friend moved away) so I can't try out other mouthpieces to see if another one fits me better. I definitely know that there is such a thing as 'too shallow:" I own a Schilke 13A4a and I can't produce any sort of tone on it; my lips just can't vibrate! I also know that I tried out a friend's Bach 3C and it was kind of uncomfortable; it felt too constricting width-wise. I have no idea why, maybe I'm just weird? Anyways, long story short: I completely understand that the matter of mouthpieces is up to personal preference, but (in your personal experience) is there a point where a mouthpiece just becomes too big (width or depth) and it begins to affect tone/range development?