How To Install Long Tube Headers On An S550 Mustang (15-23)

• A-lift or jack stands
• Torque wrench
• 3/8 drive extension
• Swivel
• 15mm deep socket
• 13mm deep socket and wobble socket
• 10mm deep socket
• E6 inverted torx socket
• T40 torx bit
• Thread locking compound
• Anti-seize
• Zip ties

INSTALL STEPS

1. Remove the battery cover and disconnect the negative battery cable.


2. Remove the cold air intake assembly.


3. While in the engine bay loosen and remove the upper nut securing the factory manifold to the catalytic converter piping. (Can be easily managed with a long 3/8 drive extension, swivel, and a 15mm deep socket).


4. Also, while you’re in this location loosen and remove the passenger side motor mount nut.


5. Loosen and removed the driver side motor mount nut.


6. Once vehicle is fully lifted you can now remove the catback exhaust and this will require additional help.


7. Loosen the 4 nuts on the sleeves that secures the catback to the midpipe.


8. Loosen and remove the (2) 13mm bolts securing the IRS cradle hangers.


9. Loosen and remove the (4) 13mm bolts securing the muffler hanger to the frame rail (2 bolts pers side)


10. Dislodge the muffler hangers from the rear frame rail.


11. Dislodge the IRS cradle hangers from the IRS subframe and have a friend slide the catback out of the sleeves towards the rear and set aside.


12. Before removing the passenger side catalytic converter assembly, disconnect the lower oxygen sensor. (removal of the sensor is optional)


13. Loosen and remove the lower catalytic converter piping to manifold nut and support the piping so it doesn’t come down and set aside.


14. Remove the starter by loosening and removing the 13mm nut which secures the large wire with the deep socket then remove the wire and reinstall the nut with a couple of turns.


15. Do the same with the other wire except it is held with a 10mm nut.


16. Loosen and remove the upper 13mm retaining bolt. (Please use a long 3/8 drive extension and 13mm wobble socket)


17. While supporting the starter with a free hand, loosen and remove the lower 13mm stud and the starter can now be removed.


18. Support the engine and trans from the bellhousing and go ahead and lift the assembly a little. (Note: if you have an automatic transmission be aware of the cooler line. Also we advise if you have 2018+ Mustang to not support the engine and transmission by the oil pan.)


19. It may also help if you loosen the (2) 15mm transmission mount to crossmember nuts. DO NOT REMOVE COMPLETELY


20. If it helps dislodge the starter wire harness clip and position out of the way.


21. To remove the motor mount bracket, loosen and remove the lower rearward 15mm nut


22. If you have an automatic loosen and remove the 10mm nut on the front side of the bellhousing that secures the cooler line.


23. Remove the cooler line brackets from each stud and position the large bracket out of the way underneath the oil pan.


24. Loosen and remove the upper rearward 13mm bolt.


25. Loosen and remove the 13mm stud. The lower frontward hardware is also a nut and stud.


26. Loosen and remove the 15mm nut and remove the wire and position out of the way.


27. You will need more leverage since the stud is tighter than the nut so you will need to place a 3/8 drive extension through the small opening in between the k member and steering rack boot. You will also need to add a deep socket and wobble adapter to the end after passing through the opening. Loosen and remove the 13 mm stud.


28. You will need the same setup from the last step to remove the upper frontward bolt, except it will be passed in between the k member and large electrical harness.


29. Lift the engine as needed and remove the motor mount bracket.


30. Disconnect the upper oxygen sensor connection located at the rear of the cylinder head.


31. Loosen and remove all 8 of the manifold to cylinder head retaining 15mm nuts. Note: once the 8 nuts are out of the way you may need to remove a few studs from the cylinder head to fully remove the manifold. You will need an e6 inverted torque socket to remove these studs.


32. Remove the factory manifold and gasket and make note of the gasket’s orientation and condition which will be a good time to replace if needed.


33. Install an oxygen sensor extension into the factory connection at the back of the cylinder head and wrap the extension alongside the transmission and temporarily out of the way.


34. Before continuing you may need to remove the passenger side motor mount for extra clearance to work. If so there are (2) 15mm bolts that can be difficult to remove because of the thread locking compound.


35. Depending on what brand header is being installed the orientation of the factory studs could differ. We recommend reusing as many studs and retaining nuts as possible.


36. First you will need to test fit the headers to see which locations can fit the factory hardware. Note: be mindful of the spacing between the header flange and the primaries as this will determine whether you can reuse the factory hardware or not. If it CAN’T be reused, make sure there is enough room for the new hardware after installing the header.


37. We recommend adding a bit of anti-seize to this type of hardware.


38. Make sure the gasket is in place then install the header. Depending on the header it might be able to just sit in position, if not loosely tighten some of the hardware.


39. Now that the header is in place, snug down the hardware in an even manner since you won’t be able to use a torque wrench but be careful not to overtighten the aluminum cylinder head.


40. Once the hardware is tightened you can reinstall the motor mount if removed then the bracket. (Remember the upper hardware are bolts and lower are studs) Once tightened, lower the engine back on to the motor mount.


41. Reinstall the ground wire at the front of the bracket


42. Reposition the cooler lines and retighten the associated hardware.


43. Reinstall the starter and 2 wires.


44. Now move to the driver side and everything is the same except you will have much more work room.


45. You will first need to separate the steering shaft from the steering rack and will need to mark the shaft and universal joint with a paint pen and loosen and remove the t40 torx bolt. Slide the steering shaft out of the joint and set aside. Make sure that it doesn’t rotate or you can lock the steering column prior to disconnecting the shaft.


46. With the steering shaft out of the way, remove the motor mount bracket followed by the (8) 15mm nuts. Before removing the factory manifold, don’t forget to disconnect the oxygen sensor connections.


47. Just like the passenger side, determine which studs can be reused and test fit the header after installing the gasket.


48. Tighten the hardware in the same manner as the passenger side.


49. Reinstall the motor mount bracket and hardware.


50. Re-connect the steering shaft and make sure the marks are aligned with one another.


51. Apply blue thread locking compound to the pinch bolt and torque it to 35 lb-ft.


52. Lower the engine and re-tighten the transmission mount to crossmember nuts if it was loosened.


53. Remove each oxygen sensor from the factory piping and apply anti-seize. DON’T mix up the 2 sensors.


54. Reinstall the upper oxygen sensors and tighten down.


55. Install an extension on the driver side and connect each sensor. Use zip ties to ensure the harnesses are as far away as possible from the exhaust piping.


56. Depending on the brand of header install the extension pipes and use the appropriate clamps to secure to the header collector.


57. Reinstall the rear sensors and zip tie away from the exhaust piping as well.


58. Have someone help with the reinstall of the catback and tighten all of the hardware associate with the catback. Double check all of your work under the car.


59. On the engine bay, reinstall and retighten the motor mount nuts.


60. Reinstall the cold air intake assembly and reconnect the negative battery cable. Double check all of your engine bay work.


61. Once you load the tune, check the car for any exhaust leaks. Realize there will be weirds smells and smoke for a few minutes as the assembly oils burn off the piping.


62. After our dyno here are the results!


That’s it! Please make sure when installing they are in accordance with your local laws and regulations to avoid any trouble.

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