I know this all too well! Just got out of an 08 MS3 and gotta tell ya we all give the 2nd gen owners heat for it.
Anyway... All the ST needs is the normal Titanium front end (with the black housings and such) and just make the entire front grill functional with a nice sized FMIC behind it! Give it sportier fogs/surrounds but the grill on the 2012 looks mean as it is if you ask me. I love it.
I was watching Roary the Racing Car with my 3 year old last night, and I swear I saw a new Mazda 3. Had to look again, sure enough when he was laughing, and facing direct at the camera, he looks exactly like the Mazda 3.