By the way, welcome to the forum.

I'd say start the engine up and see if it runs well before investing time and money in it. There ought to be someone in your area that will lend you a muffler to test run the engine before you go out and buy one. I got very frustrated as did many others using this engine. Ultimately I took all MDS 40 engines out of service although I still run the .25's.

http://www.rcuniverse.com/forum/m_20..._1/key_/tm.htm

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