It is the Abell muffler. I got a solid 600 rpm increase over the stock muffler it is a little loader but not to much. Abell told me that it will gain more rpm if you cut a little off the single stack. I just removed 1/2 inch so I'll report back what it does.

My field has no noise restriction but it could be if your does.

http://www.abellrc.com/ABELLRCHOME.htm

Thanks to all for helping me with the props and engine(it been fun)........Where do you guys buy Mejzlik props from?