Factory built cars are designed for ease of assembly in the factory, and like the NVH modifications these design factors dont always equate to the most optimum performance. The tubular headers on the Mustang's 302 are another example where performance was once again reduced from the factory. Granted the tubular headers were a great improvement over the cast iron exhaust manifolds used in the pre-85 Mustangs.

Ford's factory headers are crimped to allow them to be bolted on easily during assembly. The resulting crimp reduces the interior diameter of the header by as much as 50%. By adding a set of shorty headers it is possible to gain as much as 25 horsepower in just a couple of hours for around $225. This can be accomplished with a ratchet, sockets, extensions and a universal joint or two. You may also need a razor blade for scraping old gasket material from the head and a screwdriver for removing the thermactor hoses. A floor jack and jackstands are also a necessity.

To keep your headers looking new you can paint them with jet hot to keep them from rusting and changing color. Let them dry thoroughly be fore putting them on.

1. Begin by disconnecting the spark plug wires from the spark plugs and move them out of the way. Write down their order if you don't think you can remember where they will go.
2. Chock the rear wheels and jack up the front of the car.
3. Support the front of the car using jack stands placed under the front subframes.
4. Remove the two bolts holding each header to the H-pipe using a 15mm deep socket. If you still have catalytic converters this is best accomplished using a universal joint or two.
5. Slide the retaining collars down so they clear the bolts on the header flanges.
6. Begin removing the header bolts from the driver's side header.
7. Gently bend the dipstick out of the way and remove the header.
8. Scrape any old gasket material from the head using a scraper if necessary.
9. The new headers should come with a new set of gaskets. You may find it easiest to put a few dabs of RTV Blue gasket sealant on the gasket to adhere it to the head. This way you won't have to fight with it while you put the header on and you will also know that it's in the right position. You may also want to trim the gasket ports with a razor to match those on the head.
10. Thread the dipstick through the new header and align it with the H-Pipe
11. Hand tighten the indluded header bolts, don't forget to use a thread locking compound.
12. You will need a small 11mm box wrench if you use the bolts supplied with the headers. You can also buy a set of header bolts with hex heads for allen werenches which may be easier to install. I used some from Mr. Gasket Co. called Ultra-Seal Header Bolts, Socket Head 3/8" - 16x3/4" #916
13. Tighten the bolts to about 15 - 20 ft/lbs beginning from the center and working outwards in a pattern like this:

    7 5 3 1 2 4 6 8

14. Torque down once then go back repeat. You will need to re-torque them again in a few days after the motor has heated up and cooled down a few times.
15. Now start on the other side. You may need to remove the thermactor pump (smog pump) hoses for better access.
16. Repeat the same procedures for removal and installation on the passenger side.
17. Slide the header flanges on to the bolts and tighten them down to 25 - 30 ft/lbs.
18. Reconnect the spark plug wires and start the car up.
19. Check for exhaust leaks.
20. You may notice a burning smell for a few minutes as the headers warm up. This will go away after a few minutes.