I just looked at mine. I have three holes. I didn't run it so I don't know if any exhaust blows out. I wouldn't be surprised if some exhaust is supposed to blow out as that would expedite the removal of moisture. Remember, these are double walled pipes. The outer pipe is purely cosmetic. Also, I don't think the bulge is part of the cat. The mufflers have the corrugated mess of catalyst inside them. That's why they weigh ten pounds each!