I wouldn't mess with the plastic connections, or anything associated with it. As Z points out.
Regarding your question pertaining to a check valve or what have you, to the right of where I tapped..... no clue. That is from the factory.
I would stay to the left of that, cut just what you need out of the booster line to fit the length of that doo-hickey you're buying, and call it a day.
Cut less, NOT more!