I would like some insight on what to look for and cause and effect of egt readings when tuning.I have the whole afr concept down,but have never used egt readings to help tune so what should I be doing/looking for?I just installed a new cam/turbo/manifold&downpipe so I need to do a retune anyways and this is a good chance to learn.

examples..
What egt should I be looking for at idle,crusing,low load and wot under boost?
what effect does ignition timing have on egt's?
could I use egt readings to help set ignition timing and if so how?
what effect does afr have on egt's?

 

retarding ignition timing makes the spark start closer to TDC which creates an incomplete burn, so to say, because peak cylinder pressure is occuring too late. This means that the heat from late combustion runs out of the exhaust valves and increases EGT.

there's more to it than that, but that is about the extent to what i have personal experience with.