I did my headers and high flow cats at the same time, I can't see how you could do headers and remain sane with the mid pipe getting in your way the whole time. After killin myself on the headers the midpipe went in super easy. I recommend replacing the flange bolts while you are at, mine were in rough shape.... also, when you do manage to get the headers on, take a spin around the block with open headers to give yourself a little treat!
EDIT - I see you finished... and you had a lift? Cheater! Congrats, she must feel like a new animal after all that!