RE: Can you run a gas motor with no muffler?
The answer to your original question is yes, you can definitely run an engine without a muffler, and it will not hurt the engine. It will be incredibly loud however.
The ONLY muffler that increases power is a tuned muffler such as a tuned pipe, canister, etc. All other mufflers decrease power to varying degrees.
It is a common misconception that an engine needs back pressure. A bit of back pressure helps a glow engine to idle better because it helps keep the glow plug hot, but in all other cases, back pressure is not needed nor desired. And tuned pipes do not work on back pressure, they work with sonic waves.
AV8TOR