I am getting close to finishing a scale spitfire and want to hide the exhaust. There is no after market muffler that will even come close to being able to hide in my cowl. I was thinking of making my own and if it goes well pipe it into the scale side exhaust. I was thinking of using brass or copper with silver solder. The engine is a TT.60pro.

Is there anything I should be aware of?. Will silver solder hold up ok?. Is there a specified formula for max. outlet opening, chamber capacity etc. As you can see this is my first attempt at constructing a muffler/exhaust diverter. After this project it's on to my 1?4 scale cub. Thanks for any help you can offer.
Peter.