Drilling and tapping
Afternoon,
Not trying to be a smart _ _ _ or anything but you guys are way over thinking the drilling deal. I personally have drilled way over 100 manifolds for pyro's , Ford, Dodge, GM etc all of them. All you do is drill it, thread it and insert the probe, start the engine and let it idle for 10 seconds and then go and run it. Any particales that are left in the manifold will go past the wheel as such a low velocity at idle and down the pipes. I have never used a magnet, grease, started with a small biat and worked up left the engine running or anything else. I know it's kind so scary but you won't hurt anything at all.
Mark @ DPPI