Ok for one the WRX does not respond well to a CAI, unless programed for it. Also the wrx's are renound for having weak tranny's. In these cars you should treat the tranny with respect, no launching on pavement and no slamming gears. I guarentee if your friend is driving his wrx hard, one day he will tell you that his tranny is ****** up(fuoops). The STI tranny is a different story all together. I have never ridden in a MS3, but oncw off the line you should catch up pretty quick. Just dont miss your gears. LOL I have to laugh when I hear people say the missed 2nd. Drivers race though, good luck