My stock pads lasted me about 7,000 miles... They are wear items - the more/harder you work them, the quicker they go.
From the June 2001 Tech Tips:
(06) 2002MY IMPREZA BRAKE ROTOR "SCORING"
2002MY Impreza brake rotors are treated with Da-Cromet, a silver colored rustproofing, which
will help keep the rotor surfaces from rusting during the initial stages of transportation.
Appearance of the front brake rotors (looking like they are scored) comes from the ingredients
of the Da-Cromet coating and the brake pad material. When heated due to repeated and sudden
stopping, the coating turns into a grain-like substance and adheres to the pad and rotor. This
gives it the appearance of looking like the rotor is scored.
Some of the Da-Cromet grains are usually left behind on the rotor surface and the brake pad.
This material will look like a silver line/score on the rotor surface. After several thousand miles
of driving, the grains and lines will disappear from the rotor surface.
The Da-Cromet coating tends to easily create this condition on the 2002 Impreza rotor due to a
reaction of the pad material (which is different from other models) reacting with the coating.
Because of the performance requirements of this particular brake pad, no changes are pending.
The Da-Cromet grains/lines will not influence the performance of the braking system or
contribute to any noise condition. The rotors should not be cut to eliminate this appearance of