Found this NGK part number decoder pic... for the plugs you're asking about:
B = 14 mm thread diameter
K = hex size 5/8
R = resistor type
5 = heat rating, slightly hotter than you probably want
E = 19 mm thread reach
IX = ?
11 = 1.1 mm (0.044") wide gap, which is a little bigger than you want - that should be regapped to around 0.030"
I'd say probably the most highly recommended plug for your car (and other 06+ WRXs and 04+ STis) would be NGK's LFR6AIX plug, which is stock heat range and made of Iridium. It should provide a good spark and good performance for 60,000 miles on a stock to slightly modded (Stage 2) car.
L = thread reach 26.5 mm (dunno why this is mentioned twice)
F = 19 mm (3/4") reach, 20.6 mm (13/16") hex
R = resistor
6 = stock heat rating, I think
A = firing end construction, ok
IX = ?
07 WRX (Albins 5MT + Blouch 20G)
Jorge Carrillo Tuned (365 whp/340 wtq)