I bought a nexus egt gauge and have a couple install questions. The probe slides into an eighth inch npt couple and is secured with an allen set screw. First question is it seems like it doesn't really seal since it slides into the npt insert fairly easy, so is it really sealing?? Second question has to do with using the predator--do you have to totally disconnect the power to the gauge or just put a switch in the ign wire feed to the control unit?? Thanks.