Heres a link to my post about my install of the AFE Y pipe with pics of it and the broken studs. I also included pics of what the broken bolts looked like.
http://www.wranglerforum.com/f202/afe-y-pipe-install-1837826.html
The main thing I found out and noticed was time is your friend this is not something that can be rushed. With the home brew penetrating liquid I used or any penetrating liquid is apply it liberally and often and let it soak for a few days. Cant use too much of it. Also I used a torch with MAP gas (yellow bottle) due to its higher heat. I know this is a YJ post and its way older then my hardware but it is the same general idea. My broken bolts were long enough that I was able to grab them with a pair of vice grips and slowly I was able to turn them. When I got resistance on the bolt or I lost my grip on the bolt with the vice grips I would just reheat the bolt with the torch and start over. Lastly I can recommend this is a job to due with long sleeves. I did the job during the summer time and it was hot so I used an old knee length tube sock that I cut the toe area off and wore it like a sleeves. The red hot pieces of the bolt while using the vice grips would break off and fall onto my arm and gave me some good burns until I came up the sock idea.

 

I just cut mine and used an air hammer to knock out the studs. A punch and hammer should work fine, but you'll be fighting gravity.

 

Thanks for the replies. I was thinking if using an air hammer with a pointed tip. It doesn't look like they will spin out seems like they are pressed in.

 

I used a pointed tip since that's all I had at the time. If I were to do it again, I think I'll use my bit with a flat face, like a framing hammer.

 

Well 4 drill bit sizes and air hammer and 45 minutes and one side is out

 

Damn... Mine popped right out with no PB B'laster or heat... And it was a Missouri Jeep...

 

Mines a Jersey Jeep from near the beach