The patented 3W-muffler had been designed and tuned to suit our engines. The mufflers insures a good power output and excellent running characteristics in the mid range. The sound level had been minimized. Our different sizes of muffler will suit a wide range of models. Important message ! Please select the size of muffler according of the cylinder capacity and not whether it will fit the dimensions of the model. Mufflers being too small in volume  will damage the engine. The correct length of the header is of great importance to achieve a proper running of the engine. If the header is too short the engine can be overheated and get damaged. Running  characteristics will get bad. In case the muffler will not fit in your model , you should accept its modification even it will cost some additional work to give the engine a good performance. A correct made muffler will protect valuable models  and will prevent the engine to get damaged.