Posted for "George Braly" <gwbraly@gami.com>:

 I think you would want to be as far off of peak TIT as possible,  but doing
that ROP introduces the possibility that the exhaust would then “burn” again
when it left the crack in the exhaust plumbing.
 
 So,  doing it LOP would be nominally “better”.
 
 But the lower power settings alone almost guarantee modest temps.  The MORE
important issue is the lower the pressure in the exhaust system so that you
don’t “squirt” the exhaust out of the leak at high velocity.
 
 Also,  if you are flying a twin engine airplane,  I suggest that you just
feather the engine if there is any unexplained loss of manifold pressure.
 Trouble shoot the engine on the ground.
 
 Regards,  George
 
 PS.  One other issue.  If you land,  make sure you do not do a “go around”.
   For some reason,  pilots appear to try to do go-arounds during approaches
with exhaust leaks/engine compartment fires.  That is always a prescription
for disaster.   I  can think of  two ugly crashes that could have had  good
outcomes - - except for an ill-advised effort to do a go around in a single
engine airplane with smoke coming out of the engine compartment.