I've looked into this before and is definitely something I'm going to do. 108deg running temperature makes me very nervous and uncomfortable! Sourcing the right thermostat however was proving tricky.....they were even on back order from BMW with no available date when I last looked.

I got a few part numbers too for various possible options although ultimately I'd only really be happy with a genuine thermostat for reliability - I was looking into other options as the BMW ones didnt seem readily available...

90Deg :
BMW 11531704704

95Deg :
BMW 11531702279

88Deg :
BMW 11 53 2 248 542
BMW 11 53 1 715 254
BGA CT5003
FIRST LINE FTS473.88
MOTORAD 603-88
TRISCAN 8620 24388
VEMO V20-99-0161