Here's the main aluminum Muffler body taking shape in the spirit of the Dynomax Ultra-flo's. Unobtanium is building them since I have no time at this time.
They will also be straight thru design for max flo under throttle. Should weigh in the range of 6-7 Lbs each when finished.
Compare that to 13 Lbs each for the steel Ultras. I'll put them both on the scales when finished and get the exact numbers.

I'll probably coat the insides of the tubes before installation for max corrosion protection from the corrosive gasses like what Mr.P-body had mentioned before.