Great info KS...
I've heard through various sources that all BMW's parts are hardcoded to their VIN's... So, even if you found a 330i ecu and put it into a 325, it would still act like act like a 325i. I'm not sure exactly how it works, or if it's even true or not.
Our cars have been out for almost 2 years now, and I'm really surprised that no aftermarket company has cracked this.