Marc Christ
Brand Manager, Modified Mustangs & Fords
February 5, 2014
Photos By: Team MM&FF, Courtesy Of The Manufacturers

Bolt-on parts have been at the core of Mustang performance for a quarter-century. It's exciting to order a part from a manufacturer or mail-order company, install it yourself in your driveway, and see and feel results. The aftermarket is packed with Mustang-specific parts that we know work—because we've tested them—and they're just a click or phone call away.

But lately, lines have become blurred, and there seems to be some confusion over what a bolt-on is exactly. And since there's no sanctioning body that is the authority on what requires a part to be a bolt-on, there has been some debate over this. Furthermore, keyboard jockeys use the term to create their own micro-records for Internet fame or to boost their self image. So, we're going to give you our definition, and based on that, give you some true bolt-on options for your Stang or other fast Ford.


Bolt-On

noun — A performance-enhancing OEM or aftermarket part that can be installed in place of a stock component without fabrication, the use of specialty tools, or modifying or otherwise altering the stock long-block


Cold-Air Kits

One of the most popular bolt-ons is the cold-air kit or cold-air intake (CAI). Stock airboxes are notoriously restrictive, and a simple way to free up horsepower is by increasing inlet airflow by replacing the stock unit with an aftermarket CAI. These kits usually include all the necessary mounting hardware, and are usually built to accept the stock mass air meter. Tuning may be required, but most handheld tuners already have a CAI modification built in.

The term cold-air stems from the idea of piping cooler air into the engine by placing the inlet of the intake away from the heated engine bay. Cooler air is denser, and will therefore enable your engine to make more power than it would if the intake air was hotter.

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"We have tested tons of kits, and each and every time, we make more power with the filter in the fender well," said Jay Tucker of JLT Performance. "Not only are you getting cooler air, but you're getting consistently cooler air. Not every body style allows a filter in the fender well, like on the '05-current Mustangs, so more time must be spent on the heat shield to block engine heat at low speed, but also allow fresh air to get to the filter as speed increases."

"Nowadays, it's not only about cooler air—looks play a huge roll too," said Tucker. "Many kits are made of plastic, carbon fiber, and color-matched options, allowing you to pick a one-of-a-kind intake that looks good and makes power."

Cold-air kits are easy to install, usually taking 30 minutes or less. And prices range from just over $100 to over $550 depending on the manufacturer, application, and material from which the product was made. If you have yet to turn a wrench on your Stang, this would be a great first-time install.


Mass Air Meters

Mass air meters (MAF), or more specifically, MAF housings, are another way to reduce intake restriction. Prior to 2005, OEM vehicles were typically equipped with a plastic or aluminum MAF housing and the meter was installed into it. On those vehicles, you can simply replace the MAF housing with a larger diameter one. The new housings typically come equipped with a new meter calibrated for your injector size, so no tuning is required. Some of these require an aftermarket CAI for proper installation.

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On '05-up vehicles, you have to install a complete CAI, since the meter housing is integrated into the stock air intake system.

"Most kits on the market for the '05-'14 Mustangs require tuning," said Tucker, "because you're taking the MAF out of the factory housing and putting it in a much larger-diameter tube. The computer doesn't know that, so tuning will basically put the MAF in spec with the larger hole, preventing it from running lean."

Prices range from about $200 to over $300 for a reputable MAF housing, and usually take between 30 minutes and an hour to install.



Throttle Bodies

The throttle body is the infinitely adjustable valve that allows air into the engine based on pedal position, or pedal position and the demands of the PCM. It consists of one or two butterfly-style valves or throttle blades. The air flows through the bore(s); depending on the size of the bores, yours may be restricting airflow into your engine, even at WOT.

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Aftermarket throttle bodies increase the size of the bore(s) and blade(s), effectively increasing the amount of air going to the engine.

"The throttle body itself is easy to bolt on," said George Klass of Accufab Racing. "It's just an air valve. But to make the engine run like a stocker, it may take some computer manipulation." This is especially true on drive-by-wire throttle bodies, which require a re-tune.

Throttle bodies range from about $200 to over $600, depending on brand and application. It goes without saying that a combination of a CAI, MAF housing, and throttle body is much more effective than any of these three alone. They are the trifecta of minimizing restriction before the intake manifold.


Headers

Headers are tubular exhaust manifolds that replace the stock exhaust manifolds. Of this list, headers have the potential of freeing up the most horsepower. On the other hand, they are the most difficult to install. When it comes to what we consider bolt-ons, this is where we draw the line. Often, the engine mounts must be loosened or removed, and the engine jacked up to make room for installation. Plus, it can be quite difficult to reach the bolts or nuts that attach the flange to the cylinder head.

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Still, we think they're worth the time and effort. Stock exhaust manifolds adhere to strict rules set by the manufacturer, and power is often left on the table. Vehicle assembly and packaging are also taken into consideration, limiting the options.

"The factory parts have to be unbelievably restrictive to meet emissions standards," says Nick Filippides of American Racing Headers. "A good set of headers takes what the cylinder heads were designed to do into consideration and helps them perform to the best of their ability."

There are a slew of types and sizes of headers available in an array of materials, finishes, and price, but there are three main types—short-tube, long-tube, and mid-length.

Short-tube or "shorty" headers are stock-length and attach to the factory mid-pipe. These are available in either equal-length or unequal-length designs. Equal-length shorties have the potential to free up more horsepower, since the equal length of the tubes promotes better scavenging. Scavenging is the ability of the headers to remove as much spent exhaust gasses out of the combustion chamber as possible while the exhaust valve is open.

Long-tube headers can be even better at scavenging by moving the collector much farther away from the combustion chambers. Long-tubes cost significantly more, are typically more difficult to install, and require a custom or aftermarket matching mid-pipe. But when it comes to power improvement, shorties don't compare.

Another less-popular option is a pair of mid-length headers, which are simply a cheaper alternative to long-tubes, offering better performance over shorties at a fraction of the cost of long-tubes. Still, a custom or aftermarket mid-pipe must be used with these as well.