I read EGT should be under 1400 degrees, but most I think have the probe installed close to the engine, drilled into the exhaust manifold. I elected to install mine in the foreward test hole in the Pacbrake that is after the turbo. I know the temps will be lower than the manifold location, so what would be considdered a red zone ? I haven't towed yet after the EGT install, but it looks like 600-800 is the range that I see with the truck empty.