My buddy has a Big Gun full system on his Paptor and the same bolt snapped on his. He couldn't get it out either, so he put the stock exhaust on and took it back to the shop, it was only a month old. The shop couldn't get it either and eventually put a whole new block on the bike. Good Luck and I hope you dont have to go that far to get it fixed.

 

One of the best ways I have found is to use a nut the size of the bolt. Set it on the broken bolt, or over it if it is flush, and weld the nut to the bolt from the inside. Becareful doing this so you don't weld the nut to whatever the bolt is in. Grab the nut and turn it out like normal. It might break the nut off but just repeat it over again.