I have a set of these for someone else's project. On the outside, they look decent, Interior needs a lot of grinding, as no effort was made in construction to make them actually flow, or fit the pipes up. I am going to test fit them before cleaning them up.

This method is know to work perfectly, but it takes time and patience to cut, fit and weld. Also, must use SS MIG wire, with matching gas to get rust proof welds. I need to go back and look, but think I used 308L and argon.