Hello there I have a mild big block in my mud drag pickup. I have just been thinking about those pcv valves on the valve covers. I have just some old ones on there with a hoses on them hanging there. How important are these. I know I should have them hooked to manifold vacuum but do they make any kind of differance. I have also seen where they run hoses into the headers from the pcv valves. Does this help. Does it create more vacuum.