import_wrx

hi my cars got a apexi super air flow converter on the dash,im clueless how to work it and the guy who i bought my car off didnt know either (come with it fitted from japan)
what does this do and can it improve my cars performance?
my car also as defi gauges fitted (water temp and turbo boost) and theres a box wired upto them with rec-play-stop etc on it? doe anyone know what this is for? cheers