Bach 18C vs Curry 3 C.
The Curry 3 C. has a wider cup diameter, the Curry 3 C. has a larger throat opening.
Cup Diameter
The Curry 3 C. has a cup diameter of 16.89 mm / 0.6650 in compared to 15.10 mm / 0.5945 in on the Bach 18C — a difference of 1.79 mm / 0.0705 in. A wider cup generally produces a fuller, darker tone but requires more air support.
Cup Depth
Both mouthpieces share a medium cup depth, so the sound character from depth alone will be very similar.
Throat Diameter
The Curry 3 C. has a wider throat (3.70 mm / 0.1455 in vs 3.66 mm / 0.1441 in). A wider throat allows more air through, increasing volume and projection but reducing resistance.
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.