how to remove exhaust flange bolts

What do I have to do to these? I got the other side's flange off with a dremel and rotary hammer chisel, but now the chisel is dull and it's been a PITA to remove the bolts on this side. Additionally, i cut off one bolt but not low enough, and have destroyed all hope of getting a socket on due to the hammer drill :/ impact worked for 1/6.

 

Prayers and penetrating oil? Some heat would probably help, but i’ve got a feeling the studs might break.

 

Penetrating oil and an impact didnt work. Ran the impact until the socket didnt fit. Rotary hammer got one turning, but nothing left to grab on the one I cut off and cant reach the deep one with the rotary hammer. Feel at a loss.

 

Heavy duty bolt extractor?

 

Definitely up there in my options, though i cant fit any of my drills in the area, so going to have to get some long bits.

 

Heat would be my first goto. Preferably a torch.

Heat the flange/nut around the bolt to expand the hole, hammer on the extractor and use an extension with a breaker bar to wiggle it back and forth until it breaks free for full rotation.