Jason,
I had my full system off over Xmas and have the following to say (based on my own experiences only):
dont use pliers on the exhaust springs, use a slim Allen key as a hook if you have no spring puller. This will avoid any markings on the clips.
Get new gaskets for where the headers bolt to the engine, they are single use items only and are very cheap so worth doing.
Do not use WD40 to wipe down the headers. instead, clean them, remove all grease/dirt. Fire it up in your garage once all is fitted, it'll heat up very fast. Let it cool, wipe down with a Silicon spray. Then when it's fired up again it wil burn in and provide a clear but very robust coating helping you to clean cack off for many months to come. WD40 is not a silicon spray. WD40 is only to be used for cleaning the outside of the cans
Remove both wheels or at least the rear.
Remove the bottom spoiler.
Take your time
And finally, dont make the same mistake I did (many months before i successfully removed it) by not realising that there is a smaller section of the original exhaust that has to be removed just below the rear cylinder.
Hope that helps mate!!