About once a year I get thrown by a question from a student. This one has been asked more than once: Do you breathe in or out when striking the ball? Well, one thing I know for sure: You don't grunt! That can definitely get annoying.
If it will help your swing, think of taking a deep breath as you begin your swing and breath out in the downswing. A little trick runners use is to breath out before you take as breath at the beginning of the swing to get more oxygen. Try it! (But keep it quiet ...)
Enjoy the game again,