Bill are your "hemi" mufflers like this with center in and offset out, a perforated inside pipe?
Mike, Offset in and center out
No idea on the interior design.
I don't think the hemi mufflers have the u bends in them like the super turbo ... I'd love to cut one open ... which I read is based off a design by David Vizard ... Sonic Turbo ... according to Vizard his design didn't cost HP, he has a youtube video about them.
I remember having them on my dads 340 duster with headers back in the early 80's ... this period of my life wrecked my hearing ...
