All this said, I'd STRONGLY recommend NOT doing any kind of header (heat) wrap here!
If you want thermal protection, get it ceramic coated.
Issues with header wrap are two :
1. It traps moisture = will corrode your parts (and even 409 stainless WILL corrode)
2. More importantly, it will wick fluid leaks. If it is the wrong fluid (think oil or tranny fluid, for example) this can CATCH ON FIRE! I know a guy who lost a VERY nice GMC Syclone in Houston due to heat wrap on his downpipe.....had a tranny fluid leak, and next thing he knew the header wrap wicked it up (when cold) and caught on fire next time he drove. It was on fire and burned to the ground before he could do anything