or die grinder with any of several different style grinding heads will work quite well. Does take a steady hand but if the bolt isn't that large it is easier with a dremel. Also snap-on makes an easy out system that is spectacular with drill centering adaptors and a hex nut system that slides over the easy out so you can use socket to twist the nut out straight...no side torque.I see that princess auto is selling an identical kit currently, may not be built as tough I do not know. They ,Snap-on, also make a reverse twist drill bit that quite often removes the bolt by itself. If you pound in a square easy out you spread the bolt in the bore and it will quite often wedge the bolt and make it harder to remove. And we all know about heat.
Lastly , muffler shops have stud welders that can spot weld a stud on to another stud or piece of steel etc. Manifold bolts break off all the time so they came up with an easy cheap system to replace them. I don't know if you can take the part in to a muffler shop or not.
Sean
ps
http://www.princessauto.com/pacountr...Y=CAN&INF=home check out the sale flyer