Lose the muffler if you're sure you won't be bothering anyone.
It won't hurt the engine in any way. Just be sure to tune it right- and wear the earplugs when tuning it.
A short stack like RCIGN1 mentioned would be the best thing to do.
The general rule of thumb I go by is if you can't run a tuned pipe on a two stroke then go for least restriction possible.
Heaven forbid it will be LOUD though.