I have mine stuck with some RTV right on the blue cylinder head, the last few times I went from 90 Deg Centigrade to 100 Deg, I set an alarm in my TX for 115 Deg Centigrade, think I found lean once and it triggered, so landed straight away and opened up the needle a few clicks. It also triggered after big loops but I know it was running rich still so yes very useful as is the head speed to check the governor is working.