I pulled out some drywall to put in a new sink down stairs and I saw there is a vent already in place right there that was plumbed to have a sink! I thought great, then I pulled out a bit more drywall and saw a rag blocking the hole and thought hurm. Then a bit more and I see duct tape holding where the Y connected back to the 2" pipe with a ~half inch gap.... SO if I want to fix this, I was thinking I could cut the pipe a half foot up above the Y, put in a coupler, then add a smidge of pipe until I realized there's no flex in the existing pipe. Is using one of these the proper way to do it?