I purchased a pocketbike expansion chamber on Ebay. It was under $20. with shipping, and with some 3/4" copper, copper fittings, shelf bracket, some bending and shaping this is what I came up with. It still needs to be painted. It is very loud, but sounds great, and I hope to repack the silencer with fiberglass. I havent had a chance to take it out as it was late when I finished. Here are a few pictures and I will post performance later...

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