Also keep in mind that there is a port at the bottom that does NOT get a vacuum line at all as it is a vent. I've seen many cars with a vacuum line attached to this vent and this is not correct.

In addition, a lot of guys install all these lines to appear to be functional, but in reality they put ball bearings in the lines to "block" them off to make them dummy lines. The reason is that these switches do not always function as they should and or do not open properly thus not allowing the correct amount of vacuum etc.

Generally speaking these things are installed for looks...