Thanks for the explanation. i ordered the 14mm ID, 17mm OD vacuum hose which was connected from the intake manifold to the ICV to the intake boot. It was definitely collapsing under the pressure. I switched it out to heater hose for now until I find something more appropriate. But again, I appreciate the explanation Wayne, it's really good to get some legitimate information on these things. I'm learning little by little and this helps for sure.