I posted in the "Wanted" section that I was looking for any source for aftermarket mufflers like flowmasters pictured (or at least similar), and not much luck except for outragously priced flowmasters on Shapeways.
As "89AKurt" suggested, just make them. So, I'm now reaching out for suggestions on what to use and how. I have an idea (just popped into my head as I was typing this) but I'd like to see what you super creative guys have to suggest.