They look very good.. Thanks for the pics. What is the material?
How long are the primaries (total and for each section)? I've been holding off on building a model of the LS6 for simulation, but I'm starting to wonder what the engine will respond to.
How are you sealing the individual primaries to the collector? I haven't had much leak trouble there with other headers, but I wouldn't accept any exhaust leaks on a C5.
I've also found that getting the collector slid on the primaries can be a *nasty* job, especially if the headers have been run before. The Horror!
Either they're sloppy and they leak, or they're tight and they're a pain to get on. Clearly, you can't hammer them on.
From what I can see, you're using tabs to hold them on once they're slid all the way in place. Did you give any thought to using threaded shafts so that they can be pulled on with a nut??
Finally, did you consider band clamps instead of flanges at the collectors?
Thanks!