GCFT CDN-172: Δ>0 Physical Floor Mapping — v*(Δ) Tracks c_s(Δ), Acoustic Floor Partial, σ=16

CDN-172 maps the drag-peak velocity v*(Δ) across seven values of the spintessence stiffness parameter Δ ∈ {0, 0.001, 0.0025, 0.00391, 0.006, 0.010, 0.020} at σ=16, T=2000, using the CDN-166 linearised two-field equations with sponge boundary conditions (RK4, N=1024, dx=1). The window boundary is Δ_c = 1/σ² = 1/256 ≈ 0.00391, at which the acoustic speed c_s(Δ) = √(Δ/(Δ+4)) equals the canonical bandwidth velocity 1/(2σ) = 0.03125. Key results: (1) v*(Δ) increases monotonically from 0.036 at Δ=0 to 0.081 at Δ=0.020. (2) Above the window boundary, v*(Δ) tracks c_s(Δ) with ratio v*/c_s ∈ {1.39, 1.24, 1.15} at Δ ∈ {0.006, 0.010, 0.020}. (3) At Δ=0.020, ratio v*/c_s = 1.145 ≈ 1.144 (the Δ=0 baseline ratio), consistent with the same Cherenkov-transient overshoot governing both the gapless and acoustic regimes at T=2000. (4) The ratio peaks at 1.66 near Δ_c, a signature of mode competition at the threshold. The acoustic floor c_s(Δ) = √(Δ/(Δ+4)) is qualitatively confirmed as the physical lower bound for nucleation velocity above the window. CDN-173 (long-T runs at Δ>0) is pre-registered for quantitative confirmation. Lock code: CDN172_DELTA_FLOOR_MAP_ACOUSTIC_CS_TRACKING_T2000_SIGMA16_PARTIAL Part of Project Aporion — General Coherence Field Theory (GCFT) theory audit sequence: CDN-168 floor refuted (CDN-170) → v* ~ 1/σ confirmed (CDN-171) → acoustic floor mapped (CDN-172).