Wow, so people paid 1000+ for them and they aren't real SVS headers. I'd be really pissed. If you notice, none of the negative feedback (he only has 1 negative) is for the headers.
It would be interesting to see some dyno results with these headers. I will never pay 1500+ for a set of new quality headers, but if these things aren't total crap, 500 really wouldn't be that bad of a deal.
I sent the guy a bunch of questions, lets see if he replies.
He did refund my money promptly. I've got to tell you that the flanges were really bad, bolt holes did not align properly with gaskets and openings not matching ports correctly. The flanges were worse than a set of Hedman headers. If they were 1 5/8" - 1 3/4", I would have kept them and cut the flanges off and cnc'd my own. They were polished up real nice, but I seriously doubt they are 321 stainless either. I would have never believed that someone would go through the trouble of making Chinese Viper headers, but they did.
If your an excellent Tig welder and have major patience and skills these headers at $500 would be a great buy. I can tell you that the stainless U-bends would cost you way more than that. They did a pretty nice job of copying the Burns collectors as well, last time I checked Burns quoted me about $900 for the pair of collectors when I was going to build my own headers.
Even my real SVS headers required me to cut and re-weld the collectors to get them lined up dead nuts. Not SVS's fault but more of a production tolerance issue. Frame, motor mounts, coupled with the long wing design of the Viper exhaust will make for alignment issues.