Booyakabooboo

Ive owned Subarus for quite a few years, mostly the Legacy models. I've just treated myself to a 2012 impreza wrx sti. Very nice so far !! I've only had it a week and was looking through the owners manual and tucked inside was a Subaru performance upgrade certificate with my registration number and chassis number. The garage that sold it to me has no idea what it is. I phoned my local Subaru dealership but he wasn't very helpful or forthcoming. I emailed Subaru uk but they didn't reply. Does anyone know what this certificate could be or does every car come with the same certificate?
Any help or advice would be gratefully received.