HI Gene

If you are asking should these run a muffler, I would say yes, many many flying sites are lost due to noise. It pays dividends to be neighbor friendly and  keep the noise down.
If this is not what you are asking please clarify

Regards
Randy

HI Bill & Gene

In case that is it, I would use the muffler on break ins with all of those engines, I don't think you would overheat any of them using mufflers, As alway the caution I gave when doing this is NOT to get the motors into a lean 2 cycle, be careful to run them in richer.
I have never had any problems breaking engines in with mufflers on them, in fact engines need to be at temperature so they can break in  heat cycling at where they will operate.
I would also say use a lightly loaded prop  when you do break ins
Example  you may run a  12 x 6 on a ST G51  I use a 12 x 3 or 12 x 4 prop for breaking, I use a 10x4 or 11 x 3 on a FOX 35 for breaking. Magnum 36 I also use a 10x4

Regards
Randy