I had flanges cut out on a CNC plasma cutter thing via a drawing by my brother in law back in the day when we got along. Then bought several U's & 90's and cut them up to make headers, bolt & tack with flux Mig, then gas weld. I used 2" for the center tube & blended the 1.5" into it. I think tubes have a deeper voice, cast iron muffles.
