HELP! Yamaha motorcycle fused/seized stud help
 

Well I'm counting on the awesome knowledge here to help me out with my motorbike. I picked up a 82 Yamaha XS400J Maxim, and I need to replace the exhaust. The headers are held on with a flange that is nut on stud. Well I figured I was home safe when I soaked the nuts in liquid wrench and was able to get them to back out with no real problem. That was last week, and today I decided to take them all the way out and remove the exhaust. Well, one of them came off with the stud (no big deal, actually was better), and the other three left the studs in place.

WELL, the 3 remaining studs have fused themselves to the exhaust flanges. Like hardcore fusing. After about 2 hours of heat cycling and liquid wrenching, I was finally able to get one of them out. The way I got it loose was to put some locking pliers on the end of the stud, and then rock the flange back and forth until the stud freed itself from the flange. Once it broke loose, I could then spin the stud with the locking pliers until it came out.

Now the other side is a completely different story. Both studs are in still, so I have no means of rocking it back and forth to loosen up. I tried clamping one of the studs and rocking it, but the metal is just falling apart. I liquid wrenched it heated it with a torch about 6 times. I just picked up some LLoyds Moovit and soaked them in that, letting them sit overnight.

The main problem is that I can't turn the studs at all to get them free from the flanges around them. My locking pliers hold quite hard, but the metal plumps off before it moves. I know the stud will come out of the head no problem, but I need to be able to turn it first. Any suggestion on what to do next?

Here are some pics:
The flange with the two frozen studs:
http://www.dbmiata.com/yamaha/damnYou.jpg
The one good stud, and the other one I got out that was frozen:
http://www.dbmiata.com/yamaha/goodStudBadStud.jpg
And this is what the flanges look like on their own:
http://www.dbmiata.com/yamaha/exhaustFlange.jpg

Thanks folks!

Try welding a nut on it?

I think the main problem with that is these studs are barely sticking out. Those header pipes are really small. I put a regular M8 nut on it and it doesn't even fully fit. If I can get one of them out then the other will come out no problem. I wish I could find a small hole saw to just drill the flange around the stud...