Cat back exhaust flange. Are they bolts or studs?

how did you position the grinder? I'm facing the same issue and couldn't figure out how to make it fit with the exhaust still in place.

 

i used an angle grinder with a cutting blade. Cut on the bolt heads. Mine faced the rear of the truck. YOu want to cut them so they are flush or as close to flush as you can get. My angle grinder has a sheild on it that rotates so i had to rotate the sheild to get both bolts. You could also use a dremel which would allow you a ton of room to work. Once you get the heads flush with the flange, just use a punch and hammer them through.

 

hmmm

I'll have to take another look but I don't recall being able to easily cut the heads with my 4.5" grinder because there's a mini skid for the flange iirc