can I use a muffler from a OS 40 on a OS46 and if it does fit should the baffle be taken out?

As long as the bolt holes match up and you can secure the muffler to the engine, you can use it. As for removing the baffle, it probably isn't worth the effort. Removing the baffle will make the engine louder, but not necessarily more powerful. Your mileage may vary however, so if you have a tachometer you certainly could try it and see.