When I did my headers, I found it was much easier once I realized that loosening up the motor mounts and lifting up the engine helps a lot. I believe disconnecting the stock manifold from the down pipe was the most difficult (and it's even pretty easy with a few extensions)
also, make sure to take off the battery cable! My starter and my header made contact and it was a scary light show under there.
another thing, Make sure to wrap or re-route the wiring harness below the drivers side header. the starter wire (+12v) is under there. On my QC I also had a shift cable there that needed to be tied back. the headers get really hot and you may smell some buring plastic or rubber if you forget to tie those back.
hope that helps!