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Aftermarket Sports Car Equipment
If your car or truck needs a makeover, you don’t call the “Fab Five.” Instead, you get plugged into the automotive aftermarket and check out the companies and suppliers that specialize in making stock vehicles better looking and faster.

The aftermarket parts segment isn’t limited by the crush of production deadlines or the need to be practical, which are constant issues for manufacturers today. A chassis engineer at a major automaker may be able to spend only a couple weeks on a new suspension design, while an aftermarket suspension specialist can spend a year testing different spring rates and wheel and tire combinations in order to get the maximum cornering grip possible for the car.

Aftermarket upgrades run the gamut, from minor add-ons to major performance-enhancing modifications. Minor aftermarket upgrade options include tinted windows, a wheel and tire package to improve handling and looks, and high-intensity-discharge headlights and clear-lens taillights — popular customizing touches these days, especially with the import tuner crowd. More expensive modifications include replacing the factory-installed engine with a “crate motor” like those sold by Chevrolet, Chrysler and Ford. Some of these motors have twice the horsepower of the factory engine. Custom-made carbon-fiber hoods, high-performance Brembo brake packages, lightweight Recaro sport seats and a trunk-mounted wing are also options.

Here’s a sampling of the available aftermarket equipment, where to find it and how much it might cost. To find contact information for the aftermarket companies listed below, please refer to the Consumer Resources section.

Air Filters and Air Boxes
One of the most common, easy-to-do and not overly expensive aftermarket modifications involves “opening up” the factory-designed intake and exhaust so that the engine can breathe more deeply. Like the gearheads of the past, today’s hot rodders are far less worried about miles per gallon and engine noise — two things that limit what the factory can do — than they are about what happens when you stomp the go-fast pedal.

K&N Engineering is the big kahuna in this department. The company sells a line of low-restriction emissions-legal air filters and “air boxes” that are easy to bolt on using common hand tools, and they cost less than $100. K&N claims these products can add as much as 5 to 10 hp. Fram and Green Filter USA are two other suppliers of low-restriction high-performance air filters and air cleaner assemblies.

In addition to letting your engine breathe more deeply, low-restriction intake systems also look good when you pop the hood, and they help to produce those all-important sounds when you wind out your engine. Also, most high-performance air filters can be cleaned and reused, so you even save money in the long run. Whether you drive a four-cylinder pocket rocket or a V-8-powered pony car, a low-restriction air cleaner is a great way to free up some easy horsepower on the cheap.

Engine Controller Chips
Another popular upgrade is to swap “chips” — that’s street slang for the engine controller unit that determines ignition and fuel delivery. Most factory systems lean more toward delivering better fuel economy, while aftermarket performance chips, such as those offered by Hypertech Inc., are engineered to eke out the most horsepower.

Performance Exhaust Systems
Performance-tuned aftermarket exhaust systems, including headers, high-flow catalytic converters and low-restriction mufflers, are often the next step up the aftermarket parts ladder. Borla Performance Industries and Flowmaster are two of the biggest names in this business.

Power gains of 20 to 30 hp are common with this type of modification. The reason is that aftermarket systems, unlike many factory ones, typically use larger diameter mandrel-bent pipes that lack dimples and kinks and have been exhaustively tested — no pun intended — to achieve optimal flow rates for the particular car. Again, automakers tend to have only so many dollars budgeted for an exhaust manifold or muffler, while an aftermarket version benefits from more-focused research and design, with the singular goal being improved performance.

Most aftermarket exhaust systems are emissions-legal and retain the stock emissions equipment — a “must” in states that test emissions to obtain or renew vehicle registration. But what’s most important is that these exhaust modifications add that unique exhaust note that regular stock versions can’t create — and that’s music to the enthusiast’s ears. Look for a stainless-steel system, as these are not going to rust away and will look better, longer.

A new high-flow muffler will cost anywhere from $75 to $300, depending on the car and brand of muffler. Complete exhaust systems — which include exhaust header(s), pipes and the muffler — run from $500 to $800, and sometimes more if you want something exotic like ceramic coating or you drive a V-8-powered sports car like the dual-exhaust Ford Mustang GT or Pontiac GTO.

Superchargers and Turbochargers
The truly serious enthusiasts who have cash to burn can opt for an aftermarket supercharger or turbocharger. Superchargers and turbochargers do basically the same thing — force-feed air and fuel to the engine. The difference is that a supercharger is belt driven, like your engine’s alternator or water pump, while a turbocharger is driven by the flow of exhaust gas. Installing a supercharger is generally less complicated because it doesn’t require an extensive modification of the exhaust system.

Paxton Automotive and Vortech Engineering are two of the best-known names in the supercharger business. Aftermarket kits cost about $1,500 to $3,000 and may require professional installation. But the gains are phenomenal — an increase of 50 to 100 hp is typical, with no adverse effect on drivability, and the engine will sound like an F-16 fighter jet on afterburners when the boost kicks in.

On cars that have factory-installed turbochargers, such as the Dodge SRT-4, Mitsubishi Lancer Evolution, and Subaru’s Impreza WRX and Impreza WRX STi, a popular way to get more horsepower is to increase the amount of boost by modifying the waste gate, or adding an intercooler if the car didn’t come with one from the factory. On supercharged vehicles such as the Ford SVT Mustang Cobra and Pontiac Grand Prix GTP, replacing the supercharger’s drive pulley with a smaller diameter version increases the amount of boost and thus the amount of power. Paxton Automotive and B&M Racing & Performance Products sell pulleys for these and other supercharged vehicles.

Of course, you can always choose to increase your car’s output with nitrous oxide injection instead.

Nitrous Oxide Injection
Flipping the toggle switch for a nitrous oxide system can instantly boost the power output of an engine by 100 hp; the gas adds massive quantities of oxygen to the combustion process. The burst of speed lasts only a few seconds, but a shot of nitrous oxide can shave seconds off your 0-to-60-mph and quarter-mile times without affecting the normal operating characteristics of your engine. Nitrous oxide is an “on-demand” performance booster that works only when you hit the button. It’s a great way to get serious horsepower without having to spend a lot of coin.

Complete nitrous oxide kits cost approximately $200 to $400, and installation is a straightforward affair that doesn’t require specialized skills or knowledge. If you are a decent backyard mechanic with a good set of tools, you can probably handle this task yourself. Summit Racing Equipment offers several kits for popular models.

However, it’s critical that all directions be followed precisely — especially the part about making sure the fuel system is modified to provide the necessary enrichment when using nitrous oxide. If the engine is allowed to run “lean” (not enough gasoline) when the nitrous oxide is released into the engine, severe engine damage can result. Nitrous oxide can be a tricky beast, so seek the advice of a professional if you’re new to it.

Getting the ‘Look’
But not everyone wants to only go fast. Looks are important, too. You can buy body kits — fender flares, skirts and trunk-mounted spoilers — for the exterior.

Interior trim kits swap the factory pieces with brushed aluminum or carbon fiber, and aftermarket audio systems can deliver bass explosions that you can feel as well as hear. One cautionary note is to be careful not to overload your vehicle’s stock electrical system, especially if your car has the original alternator — it may not have the ability to keep up with the power demands of an aftermarket sound system, which can drain volts faster than Dracula sucks blood. It may be necessary, in some cases, to add a high-output alternator to handle the added load.

Probably the most popular aftermarket upgrade is to swap the factory wheels and tires for larger and wider versions. Replacing 15- or 16-inch factory rims with 17- or even 18-inchers can add instant personality, better handling and braking to practically any car. Just remember that potholes can be lethal for large wheels, and the ride quality will likely suffer.

And when it comes to wheels, always make sure that the offset and backspacing are correct. If you don’t know how to check this, ask. Never use generic, one-size-fits-all wheels that use shims or spacers. These can be extremely dangerous. Buy wheels from a supplier that has a good support line with people who can advise you and help you get a set of wheels and tires that won’t cause you problems or make your ride dangerous.
By Eric Peters for cars.com
Posted on 4/7/04