Salam alikom, great job and good hands, i like the fact that you make the design yourself which i do and enjoy a lot. . for the muffler i tried something called exhaust defuser it is made from special rubber and it is easy to install and very light. the good thing about it is that you can cut it and modify it as you want . easy to deal with and very cheap. attached its picture.
Wa Alaikum Assalam.
Thanks to participate in our subject..
May i know how I can get this item?
You are right in one side but another benefit I can get from HK item... that the pipe which I ordered is flexible and allow me to form the exhaust into any shape.