Originally Posted by Patrick Olsen
0.50mm over pistons (with pins, of course) - 6 x 12006AB860 (per Jackie @ Annapolis Subaru, there are different part numbers for '01-02 and '03-04 engines; I don't know why)
I know why
The 01-02 engines have cams with mm more lift (10.1 mm intake, 9.6 mm exhaust) requiring the pistons to have very small valve pockets in the crown. The 03-04 engines have cams with less lift (9.8 mm intake, 9.3 mm exhaust) which allowed for completely flat pistons without valve pockets. Timing of both types of cams is the same.