I agree...when temped with anExergen, it will read 190-210 or so....any of the other temp guns could very well be showing much lower or much higher....my Raytek (a good temp gun) would show about 230 or so at the same time my buddy's Exergen showed 195...also, GRP 4 plugs are the ones I used with no issues. This mill definately runs cooler then other mills..kind of like a Radical (they ran cool as well)