Part# 1046090 – 3RZ header 2000-2004

To open a printable PDF version of this instruction CLICK HERE

Kit Includes:

  • (1) Header Assembly
  • (2) Crush Gasket
  • (3) Cap Screw Hex Flange, M10-1.25X35mm, Zinc
  • (2) Cap Screw, Hex Flange, M8-1.25X20mm, Zinc
  • (2) Nut, Hex Flange, M8-1.25, Zinc

Tools Required:

  • 3/8” Drive Ratchet and Extensions
  • 7/8” Box wrench or O2 Sensor Socket
  • 9/16” Box Wrench and Socket
  • 8mm, 10mm, 12mm, 14mm Sockets
  • 8mm, 10mm, 12mm, 14mm Wrenches
  • WD40 or Equivalent

Warranty Notes:

    1. The utmost care is taken at Thorley Headers to maintain the highest standards of quality.However, Thorley Headers cannot control the installation of the product. For this reason, the Thorley Headers warranty covers only the replacement of the components - not the labor for the installation.

    2. The use of any type of “header wrapping” voids the warranty. Using any sort of wrapping material on the headers destroys the tubing’s ability to dissipate heat, causing very rapid deterioration of the metal and the subsequent failure of the headers.

    3. The chrome plating applied to all Thorley headers is a high-nickel chrome finish applied to retard corrosion. This is a “heat” chrome to preserve the metal. This finish is not “showchrome” intended for the sake of appearance. This high-nickel chrome turns colors and approaches black as it cooks into the metal. The brilliance of the chrome finish is not covered under the warranty. Contamination of the surface by foreign substances may produce other color patterns. This can be prevented by routine cleaning.

    4. Retain all paperwork pertaining to the purchase of your Thorley product. Save your receipt!Your limited warranty is not valid without a receipt of purchase.

NOTE: The installation of headers onto any vehicle must be performed in accordance with all governmental regulations that might pertain to the particular vehicle receiving the headers. Please call your Thorley Headers distributor if there are any questions regarding the legality of the installation. The Executive Order (“E.O.”) number for this part number is D-540-4.

Installation Notes:

    1. It is important that you read the entire instruction sheet before initiating any installation.

    2. Due to restricted room in the engine compartment, your headers may come close to cer-tain body and chassis components. This is normal for an installation of this type. However,a careful inspection must be completed to insure that the distances and placement arereasonable and logical, especially with regard to electrical, fuel, and brake components.

    3. Because of car-to-car variations, Thorley Headers strongly recommends that these head-ers be installed by a competent exhaust shop that has welding and fabrication capabilities.


    1. Disconnect the battery.

    2. Raise the front of the vehicle approximately 24 inches and support it with jack stands or other suitable supports. NOTE: Do not rely on bumper jacks or chassis jacks for support during header installation. The subject vehicle should be raised and supported with jacking equipment and jack stands or ramps intended for undercarriage auto maintenance. It is extremely dangerous to work under an improperly raised and/or supported vehicle.)

    3. Disconnect and remove the intake tube and air box assembly.

    4. Remove the nuts from the exhaust manifold. (Retain the stock nuts as they will be reused with the new header). Disconnect the exhaust pipe from the exhaust manifold at the 3-bolt flange.

    5. Remove the bolts from the bracket supporting the headpipe from the bell housing.

    6. Loosen the EGR tubing from the rear engine. Disconnect the EGR flange from the stock manifold.

    7. Remove the stock exhaust manifold.

    8. Clean all traces of carbon deposits from the cylinder head exhaust port surfaces using a Scotchbrite pad.

    9. Install the supplied header gasket over the studs from above the vehicle and secure the header to the cylinder head using the stock nuts. Leaving the hardware loose at this time.

    10. Attach the connector pipe assembly to the header collector using the two supplied crush gasket and supplied 10mm bolts.

    11. Reinstall the EGR tube to the new header using the factory gasket and M8x1.25x25mm bolts and nuts. Retighten the EGR tube to the rear of the motor.

    12. Re-install the two bolts to the bell housing bracket leaving them loose.

    13. When all components are in place, tighten all nuts and bolts at the head, 3-bolt flange, and bell housing.

    14. Re-install the airbox and intake tube after checking the header for proper clearance from any hoses or lines.

    15. Reconnect the battery. Start the engine and check for leaks.

    16. Re-torque all hardware after approximately 20 minutes of operation.