Update: pistons lasted 26k miles. Piston 4 broke ringlands.
Reason for failure: machine shop states: too much boost (24pounds), pistons need more than .21 piston to wall clearance if running more than 20 pounds of boost.
Overall: 05 Sti was used as a daily driver, with power gradually increasing pistons started to burn oil after 15k, about a quart a month. at 24k 1 quart a week, at 26k lots of vapor and 1 1/2 quarts a week till kaboom!. Overall tough pistons withstood lots of abuse