Andy, I just drilled & tapped the manifold. It's a ***** to do! To make the job quick and easy, you might want to go this route: Merely drill & tap in a convenient spot after the driver-side cat. That's the most easily accessible place. Drive it for a while with nothing (hho wise) running & note temp reading. Should be around 850F. Then, try it with everything running & check for any changes. It's not as accurate as manifold readings, but you'll be able to see any fluctuations.