I have modified the wheels and extended the chimney
fixing two of the shortcomings of the char griller smokin pro
now on to fire control
sealing the unit. or insulating it
Sealing. It will help keep the heat and smoke where it belongs. Insulating would largely only help in varying conditions, such as when it's cold.
Also, heat plates under the grill(s) will help spread the heat under the entire cooking surface and help with the hot side/cold side all units with a side fire box suffer from.