Bruno Tilz 305-D 5 vs Bruno Tilz 306-9 GT
The Bruno Tilz 306-9 GT has a wider cup diameter, the Bruno Tilz 306-9 GT features a deeper cup, the Bruno Tilz 306-9 GT has a larger throat opening.
Cup Diameter
The Bruno Tilz 306-9 GT has a cup diameter of 29.00 mm / 1.1417 in compared to 26.00 mm / 1.0236 in on the Bruno Tilz 305-D 5 — a difference of 3.00 mm / 0.1181 in. A wider cup generally produces a fuller, darker tone but requires more air support.
Cup Depth
The Bruno Tilz 306-9 GT has a deep cup while the Bruno Tilz 305-D 5 has a medium cup. Deeper cups favor a darker, richer sound; shallower cups provide more brightness and easier upper register.
Throat Diameter
The Bruno Tilz 306-9 GT has a wider throat (7.30 mm / 0.2874 in vs 6.30 mm / 0.2480 in). A wider throat allows more air through, increasing volume and projection but reducing resistance.
Which is better?
Both mouthpieces are categorized as "Catalog" — the physical dimensions above will determine which suits your embouchure and playing style better.