EGT's will spike with detonation..aka.. knock retard.. as far as afterburn from being too rich..nahhh..that will drop temps..lean it out they go up..watch that O2 sensor as well..it will tell you if your close.

HTH..been using an egt for 2 years on a very regular basis..some cars like 1400 other like 1700..depends..one thing for sure the turbine wheel doesnt like anything past 1750..