glow engines aren't going to be quiet. the vibration makes noise, there is reciprocating noise, the noise of the ignition and the noise of the exhaust. the more you quiet it the less power it has, and the harder it is to tune. doesn't exist man. however, the os .91 four stroke is kinda quiet, will power a 7 lb plane (if you don't need unlimited vertical you can use the .78 four stroke, same case) and you can get ultra quiet mufflers for those kinds of things.