The more info, the better. EGT's will rise if the ECU has to retard timing. It will let you know when things go south really quick;
"When the timing is retarded, the ignition process happens so late that the flame front shoots out the exhaust port when the exhaust valve opens and blows still expanding, really hot gas directly onto the EGT probe. So internally the pistons are barely warm, but the exhaust manifold and turbo get real hot. This is the reason we recommend not running EGTs higher than 900 degrees C. That is the point that timing retard is usually driving the EGTs up. Not that immediate damage is being done, it is just that you are no longer making additional power above that temperature and there is no benefit to running there. "
From High EGTs and Knock
Apexi Super AFC For The Eclipse/EVO
The wideband sensor will get cooked if placed in the manifold. It's best in the downpipe like tobz said.