If you're lucky, those bolts are just loose and you don't have a bad gasket, or worse yet, a cracked head.
If tightening the bolts doesn't work, then, like Geezer suggested, remove the bolts and exhaust gasket and replace it with new parts, just to be safe.
www.ronayers.com is a good site for OEM parts. It also has a microfiche attached to so you see parts diagrams and everything.