The main details of a header installation can be found by searching (which is how I was able to get it done). However, here are a couple tips from my installation that should help others out if they have headers planned.

Here are the parts I used:

Pacesetter Mid's (come with copper exhaust gaskets, embossed side goes toward header)
Magnaflow direct-fit Cat's (driver and passenger side)
Stage 8 bolts (I couldn't use the locks, but needed the allen key access)
2.5" Collector gasket (Pacesetter kit came with the wrong gasket to connect their slip-fit pipe to the passenger collector).
Energy Suspension Motor mount inserts
New Oxygen sensors (unless yours are fairly new and you can get them out of the old pipes)
Spark plugs and wires if needed
Magnaflow Cat-back (I already had this)


Motor Mounts:
Before starting, get some motor mount inserts. If yours haven't been recently replaced this is the perfect time to do so. I was forced to do this in-process because my passenger header was hitting my a/c box. Once the motor mounts were replaced, the headers fit fine. Taking a header off after you've gone through the hassle of putting it on is no fun, so just plan on replacing the mounts to eliminate any potential problems. To disassemble, the mounts came out by removing the section with the rubber insert. For assembly, I had to remove both mounts on each side (top and lower) and reassemble them together; the mounts with the new inserts would not go back in with the other mount still in place. The passenger mount is easy to drill out. For the driver side, take a punch and knock a starter dimple for the drill bit in over-sized rivets. Start with a small bit and work your way up in short steps to get the rivets out.
I put in the passenger side mount bolt in reverse (nut towards front) since getting it out was a bear with the a/c and power steering tubes in the way. If you can't get a socket around the thru-bolt on the driver side (due to the bolt that holds the mount into the block being in the way), jack up the driver side a tad and you'll have access (this happens from worn out mounts).

AIR Fittings:
Test fit the AIR fitting before installing to see if they bottom out. If needed, take a dremel and knock off the top thread on the AIR fitting on both headers. With mine, the AIR fitting bottomed out before making contact with the header. Grinding down the top thread allowed the male flared section on the header to mate with the female part of the fitting. This is a good tip to know since it's pretty hard to dremel this out when already installed on the car.

Just like the directions state, you'll need to jack up the driver's side to get the header in from underneath - another reason to replace the motor mounts since you'll be messing with them anyway.

Bolts:
Get the Stage 8 bolts; only for the allen tool access in the center of the bolt. One of the center bolts on the driver side header will be impossible to get to if you don't have bolts with allen access. There is limited access to this bolt on the driver side thanks to the spagetti of tubes - and an allen key is the only thing skinny enough to get in there.

Help:
Plan on being forced to take it into an exhaust shop since Pacesetter's 'slip-fit' tube on the passenger side is anything but. I actually purchased the direct-fit Magnaflow cats for both the driver/passenger and since the tubes are larger in diameter than the stock, I have to get a custom fitting made to connect these two pieces. Even if you are using the stock Y and cat's, it probably won't fit. I tried mounting my old cat on so I could drive to the muffler shop and it wouldn't fit. The Pacesetter tube would just not fit in due to the driver tube being in the way on the passenger's side cat (the passenger side cat has a tube that swings around to connect to the driver side). I had to completely hack of the passenger cat from the stock Y so I could get something mounted for the drive to the shop.


The Magnaflow driver side cat DOES NOT have a o2 bung, but the passenger side does. Don't ask me why. I drove this piece down to the local muffler shop to weld in an o2 bung (they only charged me $10) cause I wanted to use the rear o2 sensors and not worry about eliminators or a tune.

Put in passenger side dipstick after header, plugs and wires are installed; it will make things a lot easier.

Plan on bruised and cut up hands. It's unbelievably tight in there and you'll be fighting to get your hand everywhere. Also plan on this taking some time. Mine was up on stands for about two weeks since I didn't have all parts when starting and since I could only work on it at night when I had the time.

Thanks to everyone on this sight for the much needed help on getting these installed in my garage. Hopefully these tips will help someone else out in the future with their install. If I think of anything else, I'll edit this post. Good luck.

 

Amen!!!! I was so frustrated that after i installed them I never drove the car right away, and i could not of wrote something like this as there would have been a lot of BAD **%%%### words.

P.S. this could be a Sticky!!!

 

I installed these headers 18 months ago.
I have only one tip : DON'T

 

I dread the day i have to remove them as days were spent trying to get everything just right and tight. Still have leaks where they could not weld them.