I know it's tacky to put ///M badges on non M cars. That's a given. I've been thinking about a europlate for a while now, I think it would set off the front.

1989 325i w/ S50 1995 M3 Swap

My ideas were:

EXCÜSE M3
EUROKRACY
M3NTAL

(half kidding)
IMDABES

Is it tacky to have an M3 related license plate even with M3 internals?