Deflow Citroen Xantia Cuppet Screw

They could please help me if you have any mystery the
butt screws of a Citroen Xantia to remove it that game the key for trying to loosen it ... I wait for your answer thanks

Loosen the screws starting from outside to the center in a 1/2 return order and continue until they release (this is not to deform the cylinder head) with a cold engine. Use a good key to a recognized brand; Quality because they usually carry a good tightening and using a tube to make lever and cost you less. (A low quality key can only bring you problems: deform the screw head, which breaks this and "des" a blow, etc.) Greetings !!

Thank you loosening the güiro's direction while I had them with the key with the key