BBK's new headers for '05-'07 Mustang GTs come with all the usual related installation hardware such as bolts, collector studs, flat washers, lock washers, and nuts. New gaskets are also provided. Part number 1612 is the standard finish, while 16120 is a ceramic-coated finish. Installing headers on the current Mustang is considerably easier than the previous-generation SN-95 car due to the overall larger size of the S197 platform. There's simply more room to work. While it still takes a while to do the job (about 4-6 hours), the added workspace is a welcome change.
Now that we're well into the third year of production for the S197 Mustang, the aftermarket and legions of owners have had plenty of time to figure out that these cars respond quite well to bolt-on upgrades. Better, in fact, than probably any previous Mustang generation.
Not one to be left behind in the evolution of 4.6 Mustang development, BBK Performance Parts has been right there every step of the way. This is evident by the impressive results we achieved last year when installing a few BBK bolt-on bits on an '05 GT.
In a nutshell, BBK's throttle body, cold-air kit, and underdrive pulleys netted a 30hp gain over the car's baseline, and keep in mind that this was at the rear wheels, not at the flywheel. At the flywheel, call it nearly 50 hp. Not bad for a few hours work and about $1,000 in parts and installation labor-even less if you do the installation work yourself.
This time we're turning our attention to the exhaust side of engine breathing by installing BBK's new shorty headers for the three-valve, 4.6-powered Mustang GT. The results are a worthwhile step on the path to more bolt-on power.
Note that we only installed and tested the headers themselves. This includes the '06 GT test car's stock mufflers and H-pipe. Combine the headers with BBK's soon-to-be-released crossover pipe and the other above-mentioned items, and more than 300 hp at the wheels will easily be the result. It's a setup we look forward to doing, and we intend to pass on the results when a BBK test car is complete.
While having a hoist makes the job easier, it can be done with a pair of sturdy jackstands with the car lifted as high as the stands allow. In any case, you'll be switching from underhood to undercar several times throughout the job, depending on which offers easiest access to various fasteners. After disconnecting the battery, remove the top bolt of the steering shaft. For better access to this top bolt, slightly turn the front wheels so the bolt is facing directly up, which will make it easier to fit the socket over the bolt. The bottom bolt is accessed from underneath the car. | 
On both sides of the engine (passenger-side shown here), remove the nuts that hold the factory manifolds in place on the studs. | 
On the driver-side of the engine, remove the bolt that secures the oil-dipstick tube to the cylinder head. Pull the tube straight up to remove it from the engine. |
Although it might be considered optional, we strongly recommend taking the following steps because it makes installation considerably more straightforward. Jack up the engine, support it with a block of wood under the oil pan, and remove the motor mounts. This sounds more difficult than it is, mainly because there's so much more working room on these newer cars than on an SN-95 Mustang. From under the hood, begin motor-mount removal by removing the one bolt on each side that holds the motor-mount ear to the subframe. With direct access to these bolts, it takes only a few seconds to remove them. | 
From here, the work is mainly underneath the car. The next step is to remove the H-pipe. Start by loosening the two nuts on each band clamp, but don't remove them completely. | 
Pry up the locking tabs with a small screwdriver while sliding the clamps toward the rear of the car. |