Yes they are 3.5" outlets. As for removing the stockers, they were a bi!@h to get off. A lot of hammering and takin a flat head to the muffler to bend up the pieces. It took about an hour to get both of them off. I'm sure if I was home, I could of found a better way but these were the only tools I had in the trunk at the time. Got them welded on yesterday and they look sick. Will post more pics once I can wash and wax her. Debadging starts tomorrow as well.