[ironman]

You might try Googling, eBay search, or Amazon search for Go Kart Muffler.
Obviously it is going to take some "fab skills".

https://www.amazon.com/go-kart-muffl...o+kart+muffler
https://www.ebay.com/sch/i.html?_nkw...1%22&_osacat=0
https://www.gopowersports.com/1-mini...SABEgIDl_D_BwE