i changed mine yesterday, much warmer now!
its very easy to do.
remove the rubber air intake pipe,remove water pipe from stat to rad, undo the 2 bolts holding the bracket on the side of the thermostat, undo 3 bolts on the thermostat, & its off. give the surface of the stat housing a clean, & use a small amount of instant gasket on the new gasket . refitting is reverse of removal