Vacuum Line Question

[bbrugger]

I am really not interested in getting a debate started about seafoam and whether it works or not. I really want to know whether the vacuum line in the picture(the bottom of connection) is a safe place to add to get into the intake? If so, is it possible to add a can and not get any smoke at all?

I tried to look at the parts breakdown to see where the line ran to, but I could not really see. Any help would be appreciated.

Oh, just asking for a friend!