You could trim the mouthpiece down a bit or just focus on breathing through your nose because breathing through your mouth will exacerbate the gag reflex. I had that problem a lot when I was boxing and when I was playing football...hell I threw up every day when I was practicing for football, no fun at all, but at least it didn't ruin the games, I could spew and then go right back an play, in boxing I would think they would have to clean the ring, I often wondered about that