Dude!
Seriously, I have a solution to your exhaust dilemma. I had a BMW R1150GS Adventure that I put a White Bros. can on (like pictured below). Through trial and error I was able to dial in much better mid-to-high end power then the stock can had. With this in mind I spoke to older dude I know who used to build drag Sporties and Buells, he said that he had good luck with the old Supertrap that was just like the White Bros. E Series with the add or subtract disk tuning, and there's no reason why that wouldn't work for a big twin.
Granted, it might take some dickering to make it look clean, but at the same time, I can guaran-fuckin-tee you'll be the only dude with one.
EDIT: I just read your original question and I'm WAY off base here. But it's an interesting idea so I'll leave the post.
In regards to your original question, wrap the headers. Here's a pic of the first chop I ever built with wrapped slash cut.