not at all, the Euro spec S52 (the actual S52) is, but that motor is nutso, the M52 (US spec S52 B32) is a damn fine motor, i have a friend with an E30 and a M52 rolled back to OBD1 and man oh man does that thing scream. best part is its all motor power, you don't need to worry about blowing things up if you over boost or anything. and like i said, you'd have loewr miles AND could sell your old motor!!!