I've just spent a couple of hours changing the thermostat, on the 3.2...
Not a bad job to do really. The transfer pipe was a bit tough to get out of the stat housing, but slowly eased it out - didn't want to break it, as don't have a spare!
Other than that, job was no problem - the 'B' bolt is considerably easier to get to on the DBW engines - I did it with a ratchet and socket.
It's made a huge difference to the car too... the cabin heats up much quicker, and it no longer overcools on a run - so fuel economy will be a lot better too...
£25 and 2 hours well spent, I'd say!
Tomorrow's job, is to replace the cambet kit, water pump, auxiliary belt, and new aux belt pulley, all Genuine GM items.
And of course, a coolant flush, + 5 litres of red longlife coolant.
Would have done it all today while the plenum was off, but realised I left the camlock kit at my folks... durr!
Only other observation was camcover gaskets are ever so slightly weeping... so I'll be doing that over the next couple of weeks too, along with some new plugs, and an oil change.
Am enjoying getting my hands dirty once more