Megan 4-2-1 Header Installation [DIY]

Posted by on May 13, 2010 in All Models, DIY | View Comments

I performed this Megan Header install on a ’98 Civic HX (D16Y5), but the basic premise should be the same for any model. Aside from my SRI (short ram intake), this was my first real “under the car with a wrench” modification. It’s written from a n00b’s perspective (since I am one) and I hope all you first timers find it helpful.

Always use extreme caution when jacking up your vehicle. Be sure to use jack stands

Parts and Tools Needed for Header Install

  • Haynes Manual
  • Quality Floor Jack
  • Reliable Jack stands
  • Penetrating Oil
  • Wheel Chocks
  • Good Ratchet and Wrench set with various sizes
  • Cheater Bar
  • Flashlight
  • Gloves

How to install Megan 4-2-1 Header

  1. Remove everything that doesn’t require getting under the car. This will consist of the heat shield and the bolts (red) connecting the header to the engine block.
  2. Spray any rusted bolts with PB and let them soak for a few minutes
  3. Unhook the O2 sensor harness (yellow) from the O2 sensor
    4. This will allow you to remove the heat shield without removing the O2 sensor (which we will do later)
  4. After unhooking the harness, remove the 2 bolts on the heat shield and slide it over the O2 senor/wiring.
    5. megan_header_install4
  5. Now that we’ve removed the heat shield, we can remove the 9 main header bolts.
    6. This will probably require your cheater bar and both large and small socket wrench (some of the bolts are kind of hard to get to). There are still 4 bolts on the lower portion of the header, so don’t worry about it falling off.
    megan_header_install5
  6. Carefully Jack up the vehicle
  7. Make sure the car is in park, you have the parking break on, and your wheel chocks are in place.
  8. Use the floor jack to raise the front end of the car
  9. Place Jack stands under the car
  10. Remove the downpipe. This is the piece that connects the header to the rest of the exhaust system. The design of this piece will vary based on the model of your Civic. In my case, my cat (catalytic converter) is built into the header itself.
  11. The downpipe is connected to the header with 3 bolts, a mounting bracket with 2 bolts, and the rest of the exhaust with 2 spring bolts. There is also a bolt securing the header to the engine itself. We will remove this later.
  12. Remove the 3 bolts on the downpipe closest to the engine (Don’t forget about your PB).
    13. megan_header_install7
  13. Remove the two spring bolts
  14. These things were particularly hard to get off and I had to hose them down with PB several times. The secret to getting these 2 bolts off is having 2 socket wrenches, and twisting in opposite directions (one on the bolt, and one on the nut). This will cause you to remove the bolt and the nut at the same time.
  15. Once you’ve removed the 2 spring bolts, remove the two bolts on the mounting bracket near the middle of the downpipe.
  16. Now that you’ve removed all 7 bolts, take out the downpipe.
    17. megan_header_install8 megan_header_install9
  17. Remove the last bolt securing the header to the engine
  18. Unhook the second O2 sensor harness located towards the bottom of the header
  19. Lift the header up out of the engine.
  20. Installation is reverse of removal.

[source]

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