Started with a 63mm Dia U shaped stainless steel premade bend. Measured it and cut in to pieces.
Measuring and tape them together with electrical tape to make initial shape. Got a professional welder mate to TIG it together as my welding is crap.
Started it up and so loud that I had to put earplugs in.... obviously designed for a bike with a cat in it or so.... Awwwww!!! (and I like loud)
Quickly made a baffle from a left over piece of tube. I make a proper one next week.