HKS Super Sequential Blow off Valves (SSQV) are dual stage pull type relief valves that by design do not leak under high boost conditions or under idle vacuum and is actuated by pressure alterations to ensure a quick primary and secondary valve response. Right from the hks.com... It has a mounting plate for a SUBARU Impreza WRX STi 2008 and sells for $365.00. (71004-AF013)
Originally came installed on my 2008 STI when I bought the car used about 4 weeks ago. My car is still under manufacture warranty and didn't want anything to hinder me from getting repairs if I need them. Just trying to recoup some money.