That is true, but I feel they are going to be mounted close enough to the opening that I can get in there and remove the coating inside and out.

I have seen that type of probe and I haven't ruled it out. My concerns are, leaks, and consistency of mounting. This is a street car with exhaust so I don't want them to leak. It also seems very important to mount the probes as consistently as possible cylinder to cylinder and I think that would be more difficult with the clamp style and the way these headers route right out of the head.

EGT is just a data point I want to mess with, I can adjust fuel and timing per cylinder so why not try to take advantage of it?