i was thinking mabe the airflow was colling the muffler to much . so i am loosing to much heat from the muffler i an now down to about 2oz per minute and still leaving oil on the bottem of the plane. well at least now the bottem of the plane is clean ,and i am not getting all the rpm out of the motor only 5600 with a apc 20x10 i am saving my last apc 20x8 if we go the the capital zagreb for an air show. if any one has a sugustion please let me know.