first mod, remove the cheap, plastic dealer license plate frames, those never look good
as for a spoiler, it's up to your taste
BMW ///M-technic:
AC Schnitzer 3-piece:
Hartge: (discontinued so good luck finding one)
Hamann:
custom-fit wings are the only option on these cars since there's not a lot of universals that will fit, FYI, the one posted by Maverix is made for an E36 coupe or sedan, and will require extensive modification to the mounting brackets to fit