HELP! Dynatech header people

I recieved my new Dynatech header system for my 07 z/51 today. It's too late to call the vendor, so I'm asking here. The cats/xpipe are 2 1/2 inches and undoubtedly correct. The header box says 1 7/8 but for Z/06! The part number on the box is 115-636300a. The instructions in the box are for Z/06, LS-7, 7 liter vettes. Are they the same, or are there different systems for the z/06 and the standard vettes? Thanks, Bill