Retorque those heads after the first few rides to avoid issues and get rid of the junk hardware.
The thermal cycling of getting hot and cold can loosen the head cylinder nuts. A spring washer can help maintain proper torque.
5 Bellville Washers, 5 – 8mm Hex Nuts, Cylinder Base Gasket and Cylinder Head Gasket $9.00 plus s&h (ORDER BELOW)