An EGT number is just a number. As Al said, it basically tells you if a cylinder is running and not much else. The design of the header can have as much to do with EGT numbers as anything. They are more reliable in zoomies than regular headers for obvious reasons. BENDS effect things, numbers included
At Chrysler we FINALLY set a standard of 1" off the head surface
for ALL exhaust reading(EGT).. before for that guys were putting
the probes in where ever they liked... and when I say 1".. thats
measured within .005.. thats why the 1".. its easy to get that
point.... over the years since O2s came around I used to set max
power based on the O2 then check with the EGTs on all the cyls
just to see what the numbers were in relationship to what the fuel
companies called out for max temps... its very close... yes guys
now days wouldnt ever think about EGT... but the top fuelers and
all those guys still use them
