Horse Sense:
When installing performance headers, take a close look at your spark-plug wires. More than likely, they'll need to be replaced due to their age and condition. Since you'll have to remove the old plug wires and spark plugs to install the headers, it's the perfect time to drop in a new set.
The Firecone1 1/2-inch-primary...
The Firecone1 1/2-inch-primary headers (made from 14-gauge steel) are perfect for our project. JBA's line of headers includes many options to fit the desired parameters of your project. Go for the extra cost of the ceramic coating-you'll be glad you did when years from now your neighbor is on his second or third set of headers. The ceramic coating not only extends the header's life, but it also reduces underhood temperatures.
Believe it or not, there are still quite a few unmolested 5.0 Mustangs running around. Just last week a friend of Associate Editor Johnson purchased an '89 notch with nothing more than aftermarket mufflers and the air silencer removed-proof that at least a few stock 5.0s still exist.
One of the first aftermarket products produced for the burgeoning 5.0 performance market was the short-tube header. Even though Mustangs wore tubular short-tube headers from the mid-'80s, the restrictions built into them for assembly-line convenience meant that an aftermarket variant could indeed improve on the factory offering. These headers were designed to replace the stockers with no modifications-something practically unheard of in the past, where long-tube headers replaced cast-iron manifolds and required extensive exhaust modifications to make everything work.
As safety is the number-one...
As safety is the number-one priority when working under your Mustang, make sure you have strong stands or ramps to secure the car before beginning. The first step in the process is to remove the manifold's retaining hardware from the bottom. If you're working on an EFI Mustang, remove the oxygen sensors so they're not in the way where they could be damaged.
These days, replacement headers are a thriving business, with several manufacturers making variants of the original shorty header. Designs for applications range from 1 1/2-inch unequal-length headers to 1 3/4-inch stepped race headers, and several types in between.
For this story, we decided to go back to one of the originators in the field of short-tube headers and call upon JBA's line of Cat4Ward headers. We chose the company's Firecone 111/42-inch unequal-length, short-tube headers for our '85 GT as the car is going to see only a few bolt-ons and not any major induction mods such as cylinder heads. Swapping out the stock, crimped-tube headers (or the old rusty aftermarket ones that might have come on your Mustang from a previous owner) is a rite of passage for 5.0 owners. We'll show you how to do it.
 On the driver side of our...  On the driver side of our '85, the original exhaust-heat control valve was still in place. This valve usually functions on a vacuum circuit to warm the engine more quickly. As you can see by the missing choke plate, this control valve was doing jack squat. |  For better working room when...  For better working room when replacing headers, it's best to remove everything in the way. Normally, there would be emissions hoses and valves in this area, but they have been disabled and removed on this car. Plug wires and spark plugs are other things to remove. Though we left our plugs in, the first-timers in our audience should remove them to prevent breaking a plug during header removal or installation. |  The factory steel-tube headers...  The factory steel-tube headers are attached to the cylinder heads with large 9/16-inch-headed manifold bolts. These large fasteners are what the assembly-line air tools used, hence the crimped areas near the exhaust outlet of the cylinder head. Remove the bolts with a socket. If your Mustang still has the factory engine lift hooks, they can be removed and discarded. |
 After extricating the stock...  After extricating the stock passenger-side header, we laid it next to the new JBA header for comparison. Which one would you want on your street Mustang? We thought so. |  The driver side is approached...  The driver side is approached the same way. Clear away any obstructions, plug wires, and so on, and unbolt the manifold. Due to the individual port-flange design of the stock manifolds, you can snake the manifold out around the dipstick tube. |  You will need to remove the...  You will need to remove the dipstick tube from the block for installation of the new headers due to their thick, one-piece, 3/8-inch flange design. Grasp the dipstick tube at its base and carefully rotate the tube back and forth while pulling upward to remove it from the block. |