I did post an offer to have my full length headers copied when I took them in for coating at Rewarder Headers, but it was going to be quite pricey....about $700 for the initial setup fee, then about $350 per set. So to make up for the initial cost, the headers would have to sell for about $400 per set. That's quite a bit of $$$ for us cheap ass Z guys.
Well, that's OK with me....at least my exhaust system will be completely unique! It took a lot of work to build those damn headers....they better never rust or get broken!!
What you could always do, is get a set of uncoated headers, and buy a 'D' port pair of flanges, cut off the round flanges from the header, weld on the 'D' flanges and have them coated. A little more work, and a little more expense, but it will be 'done right'!
Tim