Good tech info about this subject,
http://www.sdsefi.com/techegt.htm
Here's a few quotes for those that don't like to read tech articles,
"It is really the AFR that is important, not the EGT. "
"Some gauge manufacturers say you should tune to achieve maximum or peak EGT for maximum performance. This is incorrect. Peak EGT generally occurs at an AFR of around 14.7- 15.0 to 1 on gasoline. This is far too lean for maximum power and is dangerous under continuous WOT conditions. Many people think that the leaner you go, the higher the EGT gets. This is also incorrect. Peak EGT occurs at stoichiometry- about 15 to 1 for our purposes. If you go richer than 15 to 1, EGT will drop and if you go leaner than 15 to 1 EGT will ALSO drop."
"Extensive testing with laboratory quality instrumentation on aircraft engines universally indicates that best power is NEVER made at AFRs richer than 12 to 1."