Most if not all long tube headers are considered "off road" and will never have a CARB #. Take a look at the recent edition of GMHTP and Chris Werner's article on header upgrades to his 4th gen SS. He explains that the length of the tubes, which moves the cats back, causes them to fail cold-start emissions since the cats take too long to heat up. If you live in an area, oh say like the Shenandoah Valley of Virgina, where there are no emmisions tests then this is not an issue.
Regardless, these look like a very nice setup with some nice power gains.