Originally Posted by Azrael
Start from the bottom up and just take your time. Remove the O2 sensors (7/8 box wrench worked best) unbolt the y-pipe, then the cats, then the manifolds. Remove it all from underneath the car. It helps if you hit everything with penetrating oil, or something like that and then work on the O2 sensors. I actually used Break Free from my gun cleaning kit...
Taking off the passener side rear bolt and rear plug (or just the plug wire) is easiest from underneath the car after the cats are off. Remember to take your time and place bolts in plastic bags or tuperware containers and label them (if you need them again)... Our Pacesetters came with all new hardware, but we ended up droping a header bolt somewhere and never found it, but had the stockers on hand and ready to go.
Lock-tite for the header bolts when re-installing. Torque them from center out, take your time and give it two passes.
make sure you ahve extentions for your socket wrenches. Pre-assemble detail stuff like block off plates ( I got so exited about getting the headers on the car that I forgot to put the block off plate on the passenger side first and had to try to wiggle my big hands/arms into places they were never meant for...)
It helps if you have someone that has done it before, but it really is not that hard... Taking off the stock exhaust is the real PITA, check your new y-pipe fit before starting to put it on the car!
Most of all good luck!