Thanks for the info. I have that engine (3300) on a friction drive. It goes 28mph with the 1.25" roller. I wondered if the crapalytic converter was holding it back.
The stock muffler costs about $35 to replace, so I'd like to know if there is a box-type scooter muffler that will work, esp one that fits under the stock shield. If not, that's ok but I like having the guard over the muffler.
Here's some mods I did to the T 3300:
http://motorbicycling.com/showpost.php?p=376086&postcount=32 It's still loud, but not ear-ringing obnoxiously loud, and the dogs seem less interested in it. At 15mph or less, it isn't unpleasant, and at top speed, it sounds less offensive than weedeaters and blowers, sort of a changed frequency.
I think it would be cool if someone made a small, fat baffler exhaust for this engine. Maybe sometime I'll make friends with someone who likes welding, and can put one together.