Vacuum Readings...car running rough!

[RIXX93GT]

I know I probably have a vacuum leak as my lower to upper gasket on the intake had a tear in it. My question is , where is the best place to take a vacuum reading and what kind of numbers should I have when there is no leak? I have two ports after the throttle body on the intake I can tap into or should I use the vacuum tree? Help me please

 

[ss93cobra]

I don't think it really matters where you take the reading as long as you remember to cap off the other end of the hose if you do it that way. I can tell you that mine reads at about 20 on the boost gauge at an idle.