I believe this engine is also sold as the 3W 342, at least in base form. I'd then assume any appropriate exhaust for the 3w would be suitable. This suggestion, along with other interesting comments and links are found on this thread, regarding the 342:
http://www.rcuniverse.com/forum/m_34...tm.htm#3431015
Ah...I now see you have already found the above thread.

Keep us posted.
Chad