"i looked at Aero Turbines, the technology looks interesting. does it actually work?"
No!
"i like the idea of using a full titanium muffler cuz it would be lighter and never rust. stainless does rust, despite what people say."
Made of the correct steel grade and treated correctly stainless steel do not rust (a layer of chromium oxide will protect the steel)! Titanium oxidize at temperatures above 600 degC when it is in contact with oxygen, this makes titanium unsuitable for exhaust systems in many applications.