Rich, been away so only just read your post!
I found it interesting as it brought back a memory about a conversation I had with a honda elise converter ages ago.
I dont know the why and the hows just relaying what was said!
Basically I asked the question why is it that someone would spend £10,000 upto £19,000 on a honda conversion (yes that is how much they cost) but they keep the crappy expansion tank from the k-series?????
The answer was that the expansion tanks are all brand new from rover and not the old ones but the reason it is the rover tank is that plumbed correctly they found it was the only tank that did not suffer from air locks in the system??????????????????
Strange?? yes very but any honda conversion on any elise anywhere will be plumbed exactly the same with the rover tank no matter who carried out the conversion.
The tanks dont even look as high as ours are either
As I have said I don't know and you are the only one of us with the car on the road so I don't know how mine will behave yet just thought I would share this with you