The last time I has looking for flanges I had a hard time finding 1/2" thick stainless flanges with 1.75" ports. I don't like butting the tube to the face of the flange. I prefer to sink the tube up in the flange a bit then weld the outside and the inside. It also makes it a little easier when mocking up the exhaust system. I have my own flanges waterjet so I get exactly what I want. CNC flanges look cool, but the simple water jet flanges work just as well.