dennis - i totally agree with you. this is the same way I have tuned my chinese 2300s, by adding back pressure through closing down the pitts type muffler ports some, which gives you enough back pressure to get good carb tuning.

the problem with most pitts type mufflers, in my opinion, is they are built with outlet tubes which are far bigger than the engines they are sold for need.

For that matter my 2300s tune very well with the muffler supplied by super tiger with the engine. if you look at the riginal muffler you can readily see the smaller outlet area it has.

Ed