Schilke 13A4a vs Warburton 5SV
The Schilke 13A4a has a wider cup diameter, the Schilke 13A4a features a deeper cup.
Cup Diameter
The Schilke 13A4a has a cup diameter of 16.76 mm / 0.6598 in compared to 16.20 mm / 0.6378 in on the Warburton 5SV — a difference of 0.56 mm / 0.0220 in. A wider cup generally produces a fuller, darker tone but requires more air support.
Cup Depth
The Schilke 13A4a has a shallow cup while the Warburton 5SV has a very shallow cup. Deeper cups favor a darker, richer sound; shallower cups provide more brightness and easier upper register.
Throat Diameter
Throat diameters are essentially identical at 3.66 mm / 0.1441 in, so resistance feel will be comparable.
Finish
The Schilke 13A4a is listed as unspecified, and the Warburton 5SV as Silver plate. Finish mainly changes lip feel, tarnish resistance, and appearance rather than cup geometry.
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.