Kelly 3C vs Yamaha CR-DUTOT-S
The Kelly 3C has a wider cup diameter, the Kelly 3C has a larger throat opening.
Cup Diameter
The Kelly 3C has a cup diameter of 17.02 mm / 0.6701 in compared to 16.90 mm / 0.6654 in on the Yamaha CR-DUTOT-S — a difference of 0.12 mm / 0.0047 in. A wider cup generally produces a fuller, darker tone but requires more air support.
Cup Depth
Both mouthpieces share a very deep cup depth, so the sound character from depth alone will be very similar.
Throat Diameter
The Kelly 3C has a wider throat (4.06 mm / 0.1598 in vs 3.99 mm / 0.1571 in). A wider throat allows more air through, increasing volume and projection but reducing resistance.
Material
The Kelly 3C is described as Lexan polycarbonate, and the Yamaha CR-DUTOT-S as unspecified. Material affects mass, warmth, and how quickly the piece responds.
Which is better?
Neither mouthpiece clearly dominates the other — the right choice depends on your embouchure, playing style, and the sound you're after. Try both if possible.