2005 325i Auto
+1 on that.Yep, that initiative was a disaster. You can read the whole sordid tale here:
Hey guys, We've started this project! Check out the details on our blog or posted within this thread! Please feel free to chime in with comments, questions, and recommendations. http://engineering.mishimoto.com/category/bmw-e46-3-series-coolant-expansion-tank-1999-2006/ E46 3-Series Aluminum...www.e46fanatics.com
The ironic part is that the expansion tank isn't meant to be the weakest link in the cooling system; replace your rad cap with a lower pressure rating and you won't have to worry about the tank exploding any more.
I've got the GAS 1.2bar cap, and it certainly hasn't given any trouble yet in an extremely hot Australian summer. Been watching the hidden dash temp function like a hawk.