PR’s Data (2009):

Fs = 31.74 Hz
Qms = 9.1210
Qes = 0.4584
Qts = 0.4365
Vas = 93.01 Liters
Cms = 2.499E-4 M/N
Re = 7.07 Ohms
BL = 17.59 N/A*
Sd = 0.05.15 Sq. Meters
Mms = 0.10059 Kg
Ref Efficiency = 0.624 %
Predicted Output = 90.15 dB/1W/1M
Predicted Sensitivity =  90.69 dB/2.83v/1M
Xmax = 8.64 mm

*Notes say the BL crosscheck was close – will try to locate
  the exact data.