hey im new to this. i just baught a 1991 zx twin tubo and the car over heated. i did a compression test on it and cylinders 1,2, and 6 were around 120 when the engine was cold. cylinders 3 and 4 were below 60 and cylinder 5 was below 90. do you think i have a blown head gasket or is it the pistons? what should i do?