1)   If you advance the timing,  the EGTS will drop.
 
  2)   If  hold the spark initiation timing event to a constant value,  and
you
use a spark source that provides a more consistent and quicker formation of
the flame kernel,  the EGTs will drop slightly.
 
  3)       If you use a “standard” ignition source,  but advance the timing
slightly,  you get exactly the same combustion event with the same horsepower
and the same peak pressure and the same Theta-pp, as you get with item 2),
above.
 
  It is fundamentally simple.  That is all there is to it.
 
  Regards,  George