A couple months back I bought a set of used downpipes and put them on Mutato, so I figured I'd update on the installation.
The stock mufflers wouldn't fit and the Emgo 'shorty megaphone' was a disaster -- excessively loud to the point of painful.
Then one of the folks here got me thinking about muffler design so I built one. It's fabricated from 1-1/2" electrical conduit, 4" round electrical boxes and covered with 4" galvanized HVAC ductwork. The outer cover is attached with pure tin plumber's solder for a higher temperature melting point than 60/40 solder.
Most importantly, it works quite well!
The offset pipe from the header to the muffler is also conduit and the couplings are from the same source but sawed in half and filed out to fit. It's definately the ugliest way to bend pipe but gave a really smooth bend and interior. Besides, I like the post-apocalypse look...
The total price of materials was about $40 plus about another $20 for a replacement spool of welding wire.
I'm currently running #130 main jets with #40 pilots but the pilots are too large and I haven't done any 'fine tuning' on the main jet size. At least I'm not getting any obvious misfires with this setup.
Jim