i noticed something the other day pulling my motor out , its on the back of the drivers side head , it looks like it had a tube coming out of it and its held in by a bolt , well the PO welded up the tube and kept it bolted on the head , not sure what it is , probably something to do with the emissions , im just not sure if i dont swap on on my new heads will it cause any issues , any ideas what it is and if i need it ?