Soak the exhaust manifold bolts in a penetrating oil. The get brittle with heat and age.
An impact wrench is better for removing the exhaust bolts. Heating the bolts with a propane torch may also be necessary.
Get new head bolts and exhaust bolts. Use the Loctite Anti-sieze on the ex bolts.
If the bolt breaks and it cannot be removed with vise grips take it to a machine shop. Quality bolt removal equipment (ez outs, center drills etc) is expensive and easily broken. The guys that use it on a daily basis develop the skills that make it look easy.
Just my .02 worth (I hate broken bolts)
[This message has been edited by DanielKJenkins (edited 02-11-2004).]