What pads fit the stock WRX calipers?
Though the WRX is a recent addition to the North American market, there have been changes to the stock brake pad shapes both front and rear. The changes occur on or around production dates of Dec 2002 and Jan 2003. It is best to confirm the pad shape before ordering.
The Friction Materials Standards Institute (FMSI) is an association that assigns numbers to different pad shapes that are used as a guideline for pad manufacturers to refer to, and bring a common numbering system to the brake pad aftermarket. Virtually every pad manufacturer will either use the FMSI number in their numbering system or have a readily available interchange to cross-reference their part number to the FMSI number. The numbers shown with the drawings below are FMSI designations. All drawings are reproduced with permission from Centric Parts.
FMSI # D721
FMSI # D770
FMSI # D929
FMSI # D1004
