I am trying to figure out my boost noise. When under a vacuum there is a slight hissing noise. Like I have a leak. Well, I thought it was the hose so I replaced it with vacuum tubing. Nothing. Thought maybe it was the gauge so I took the hose off and plugged it with my finger. No change. I checked the throttle body spacer and there seems to be no leaks there either. I even but a clamp on the hose to be sure. I was reading on other car forums that I should add a restrictor. I was reading that you can use a small fuel filter and it will work the same. Before I go but this stuff, any suggestions?