for the purposes of IR missiles, i think its been said that DCS only considers afterburner status, mil power, or idle
in other words.. it doesn't matter if you're at full burner, or min burner, if you're in burner, its all the same
or, if you're at idle, you have a minimum heat signature
if you're not at idle, and not in burner, you might as well be at mil power
the "resolution" of your heat signature is very "rough"
if i recall correctly...