I remembered how to use the hidden menu to view temperatures and noticed mine would not go over 77c and when moving with heater on 69-71c.
Today I fitted the new stats and very happy that it now sits between 90-96c.
It was a bit fidlier than on the X3 2.0d but very doable in around 3-4hrs if taking time.
Just make sure you buy a genuine BMW Main Thermostat, the EGR stat I also got from BMW but after looking online you can get a Febi/Mahle for under £20.
Only went for a 20mile round trip to test but so far
