So what size is your exhaust and do you want to make me one
Comming out of the manifold it is 2", and after about 18" it transitions to 2 1/2" inches. It stays 2 1/2" up to the the cat, which also has a 2 1/2 " opening. Out of the cat it is 2 1/4" for about 3-4" until the muffler and then it is 2 1/2" all the way back.
The stock is 2" all the way from the manifold to the end of the tail pipe.
IF, I ever had to do it again, I would have a shop do it, or buy a pacesetter header which is the only YJ header to wrap around the front of the oil pan like the TJ's.