oringially posted by QR25DE
Header INSTALL
**Read all of this post first before the install**

install was not as easy as described by HotShots instructions Confused so I will tell you how I installed it, which I believe is the easiest way (having installed my HS header twice and removed my stock header twice)

~Tools used
-jack and 2 jack stands
-open/closed wrenches
.....10mm
.....12mm
.....14mm
.....16mm
.....22mm
-socket wrenches
.....1/4" drive
.....3/8" drive
.....1/2" drive
-breaker bars
.....1/4" drive
.....3/8" drive
.....1/2" drive
-socket wrench extensions
.....1/4" drive 3" ext.
.....1/4" drive 6" ext.
.....3/8" drive 3" ext.
.....3/8" drive 6" ext.
.....1/2" drive 3" ext.
-sockets
.....10mm 1/4" drive
.....14mm 3/8" drive
.....14mm deep socket 1/2" drive
-flat-head screwdriver
-phillips-head screwdriver
-grease, though it's not really a tool

~Brief summary
...unpluging battery cable. Step 1
...jacking up car. Steps 2-3
...removing alternator belt (via auto tensioner pulley) and alternator. Steps 4-12
...unpluging O2 sensor. Step 13
...removing old header. Steps 14-16
...removing O2 sensor. Step 17
...cleaning all ports. Step 18
...installing new header. Steps 20-24
...replacing O2 sensors. Steps 25-26
...reconnecting alternator. Steps 27-30
...removing jack stands, reconnecting battery. Steps 31-32
...turning car on/off. Steps 33-34
...checking for loose bolts/nuts/leaks. Step 35

~New Parts

      >header nut. one w/o built in washer. one of the stock nuts needs to be replaced because the built in washer hits the weld on the header (your other option is to file the header. I wouldn't reccomend cuting a seperate washer because you might create a leak). Nut size= Fine M10 1.25mm *note, this might be larger wrench size than 14mm, the one I got was a 16mm wrench size.
      >bolt (probably not). you might need to replace the bolt connected at the bottom of the header (I lost mine). The size is M10 1.25mm x 30mm
      >O2 sensor (hopefully not in your case). I replaced my top O2 sensor, though I didn't really need to. It was $60 from my local dealer. the bottom one sells for $140



~Installation
**since I seem to forget all the time...counterclockwise is to loosen, clockwise is to tighten**

      1- Make sure there is at least one person with you.
      ~There are some steps where you will need 2 people...it really helps. Though on my second install I was able to do everything alone.

      2- Unplug negative battery cable. 1 nut total. 10mm open/closed wrench.

      3- Jack up front of car.
      ~I jacked up from the thick beam under the engine that runs down the center of the car.

      4- Place jackstands underneath car. Make sure they are secure.
      ~There will be grooves just below the sideskirt on both sides of car, toward the front wheel well. They will hold the car. For added safety I used wood supports under the tires.

      5- Remove the top most heatshield from the header. 4 bolts and 2 connecters holding wires total. 10mm open/closed wrench, 10mm 1/4" drive socket.
      ~There are wires strapped to it, remove them first (they just slide off). This makes things easier to see.

      6- Remove all wiring from the alternator. There are 2 bolts and 1 plug total. Use a 12mm and 10mm open/closed wrench for the bolts, the plug will come off by hand (push on the right side and lift it out).
      ~The alternator sits just to the left of the stock header. It has a pulley on the left side and a belt connecting it to other pulleys. It also has 2 plugs connected to it, one has a red cover.

      7- Remove the passenger side rock shield from the bottom of the car to get to the auto tensioner pulley. There are 6 bolts total. Use a 1/4" drive 10mm socket, a flat-head screwdriver and a phillips-head screwdriver.
      ~There is a big piece of plastic under the car on the passenger side below the engine, it also goes into the passenger side wheel well, by removing it you can get to the auto tensioner pulley much easier. 3 bolts are located near the front of the car, the far left one is a 10mm the two to the right will just pop out with a flat-head screwdriver. Take the flat-head screwdriver and place it in a groove (1 of the 4) and up to the center round part, twist the screwdriver and it will pop off. There are 2 more bolts and 1 screw in the wheel well. The bolts are 10mm, the screw is phillips.

      8- Take the belt off the alternator. 14mm open/closed wrench. The bolt on the tension pulley must be turned clockwise. It is wise to make a crude drawing of how the belt system works, in case the belt falls off or something.
      ~To do this one person is under the car and one is by the alternator. The person under the car turns the bolt on the auto tensioner pulley clockwise, the whole pulley will move and the belt will loosen (the pulley you are looking for is just to the right of the crank pulley. The crank pulley is the bottom-most pulley. The person over the engine bay can now move the belt off of the alternator.
      ~You can also do this by yourself by placing the closed end of the wrench on the auto-tension pulley. Sitting down in front of the car and using your foot to push the wrench forward (clockwise), you can reach up and blindly find the belt and move it off the pulley.

      9- Remove the wire support harness on the left of the alternator. 1 bolt total. 10mm open/closed wrench.
      ~For the next step the harness supporting the wiring that goes to the alternator must be removed. It is gold in color and located on the left of the alternator.

      10-Remove the coolant tank. 3 bolts total. 1/4" drive 10mm socket, 3" extension + 6" extension.
      ~Remove the harness that the coolant tank is resting on, not just the tank itself.
      ~The grease trick: you're going to have trouble lifting out the bolts. Fill the socket with grease before you place the socket on the bolt. After the bolt is loose, when you lift up the socket the bolt will stick to the socket. This is also a great way to put the bolts back in place.

      11- Remove the alternator bolts. 2 bolts total, one up top and one near the bottom. 14mm open/closed wrench and 3/8" drive 14mm socket with 3" extension.
      ~There are two alternator bolts that must be removed, both are 14mm. It is easier to remove the bottom bolt first, it is a long bolt, just keep turning. The top bolt is nice and short.

      12- Take alternator off and place it aside.
      ~You might have to work at it to get it off. Just keep wiggling. You don't need to remove it completely from the engine bay, just put it off toward the side.

      13- Remove the alternator harness. 2 bolts total. 3/8" drive 14mm socket and 3" extension.
      ~The alternator harness is connected to the block and is gold.

      14- Unplug (not unscrew) the O2 sensors. 2 total.
      ~Just unplug them from the harnesses. The top one is green, the bottom one is blue. Squeeze the side coming from the engine and they will come right off.

      15- Take off the nuts connecting the header to the block. 5 nuts total. 14mm open/closed wrench and a 1/2" drive 14mm deep socket and 3" extension.
      ~The left most nut will need to be taken off by a deepsocket and an extension. I almost rounded the nut off, don't do that.

      16- Take off the bolts at the bottom of the header. 3 bolts total. 3/8" drive 14mm socket, 3" extension and 6" extension.
      ~There are two bolts with springs attached to them. They are on the bottom of the header piping, after the cat on the header. Go under the car. There is also another one that is kind of hidden. It is located by the drivers side spring bolt. Use the 6" extension and unscrew the bolt (connected via bracket). You can get to the bolt from the drivers side of the big center support bar.

      17- Remove header from the top of the car.
      ~It will come out, just keep pulling. You might get cut...and bruised when it comes out...use Neosporin, cuts heal.
      ~If you have gone in for the recall, you will need to take off another bolt. Otherwise it will snag and you will get cut up...even more. The bolt is on the four point harness, it is the top left bolt that is connected to the pre-cat. This bolt is not fun to take off...it will suck!

      18- Remove O2 sensors. 2 bolts. 22mm open/closed wrench.
      ~Now that the header is out you and your friend get to take off the O2 sensors. They will not come out without a fight. One person holds the header and the other person takes off the O2 sensor. Make sure you take the bottom one out carefully...WD-40 is your friend. I replaced the top one that will go into my new header. If you need to replace them you can get them from your local dealer...
      Top O2 sensor: $60
      Bottom O2 sensor: $140...not a misprint!

      19- Clean the header ports on the header and on the block, the downpipe on the car, the bottom of the header (where the exhaust gases exit) and the metal ring that is on the downpipe that comes out.
      ~It is important you clean these spots so that no dirt gets into your engine.

      20- Screw in the top O2 sensor. 1 bolt total. 22mm open/closed wrench.
      ~Make sure you put some sort of anti-lock grease, just don't put too much.

      21- Place the new gasket on the block.

      22- Place header into position from the top of the car.

      23- Put the metal ring from the downpipe onto the bottom of the header.

      24- Place the header nuts back on, but do not tighten them.
      ~Put the nut w/o the washer on the leftmost space. It will be on the top row. If you put a nut with a built in washer in, the washer might hit a weld on the header and will not tighten. You can pick up a nut w/o a built in washer from Auto Zone. The nut size is: Fine M10 1.25mm.

      25- Reconnect the bottom of the header. 3 bolts total. 3/8" drive 14mm socket, 3" extension and 6" extension.
      ~Tighten these ones. The header is threaded for these bolts to fit in. The welded bracket on the header should line up with the bracket on the car, either use the old bolt, or if you lost it you can buy a new one, size M10 1.25mm x 30mm

      26- Tighten the header nuts. 5 nuts total. 14mm open/closed wrench (possible 16mm open/closed wrench) and 1/2" drive 14mm deepsocket with 3" extension.
      ~The leftmost top nut (the one you bought separately) might be a different wrench size, mine was a 16mm. Use the deepsocket and extension for the leftmost bottom nut. One of the nuts may be quite hard to reach due to the bigger piping...tighten them all pretty hard.

      27- Plug the O2 sensor male end into the female end. Sex. Secure the O2 sensor wire.
      ~The top one is the green harness. I used a zip tie to secure the wire...it was sticking way out before. Dont let yours get caught in the fan.

      28- Reconnect the alternator harness. 2 bolts total. 14mm socket with extension.
      ~This was the big gold harness that holds the top of the alternator.

      29- Reconnect the alternator. 2 bolts total. 3/8" drive 14mm socket with 3" extension.
      ~Connect the bottom bolt first. You have to wiggle the alternator into place for it. Just keep pushing, it's a b!tch. The top one is easy though

      30- Reconnect the wire harness to the left side of the alternator. 1 bolt total. 10mm open/closed wrench.
      ~The other little gold harness with the wire attached to it.

      31- Reconnect the belt to the alternator.
      ~If you made a crude drawing like I told you to, this will be easy. Just go for that auto tension pulley again...with a friend to put the belt back on the track.

      32- Use the jack to remove the jack stands.

      33- Reconnect the battery. 1 nut. 10mm open/closed wrench

      34- Turn the car on and let it reach normal operating temperature.

      35- Turn the car off and check for loose bolts/nuts/leaks.
      ~Careful it will be hot.

*If you do not have a resonator, your car will sound very raspy.
*If you have cat-back piping and a high flow muffler, a "back-fire" sound is normal.
*If the header is too loud/raspy you might want to go to a muffler shop and get a bigger resonator, it will make a world of difference.


To avoid the check engine light
if you order from Performance Tuning, they will include all you need to avoid getting this light.

      ~O2 bung - this is just a metal ring where the O2 sensor will screw in. take the bung to a muffler shop and have them weld it behind the 2nd catalytic converter...if you've already done the header swap, it will be the only catalytic converter.
      ~wire extensions - you have to extend the wires that come from the second O2 sensor so they will reach behind the cat.