How to add More Horse Power to your car

1. 1 High-Flow Air Filter: K&N Air Filters are warranted for 1,000,000 miles, and can add 5 horsepower or more depending on vehicle. Also, AEM used a "dryflow air filter than never needs oil. And AEM is the only intake system to be 50 state legal. So, you don't ever have to buy new air filters, but you're also letting your engine breathe better, adding a small amount of power. For about $40-$250 for most applications, this is an excellent place to start...For better results + sound, take off your air silencer ( black tube in the fender connecting to the air box ) get more kick with a side of hearing your engine inhale.
   
2. 2
   Performance Exhaust: Have a muffler shop that knows what they're doing upgrade your exhaust system. The term for what you want is a "header-back" exhaust. That mans that it will be built up from the exhaust headers back to the end of the car (pretty much straight from your engine to the tailpipe). I-4 cars should go up to 2.5 exhaust, unless a turbocharger is equipped, then 3" is acceptable. V6/V8 cars should have 2.5"-3" exhaust all the way through. Performance Exhaust will greatly increase the amount of noise the car makes. The exhaust will change to a deep, rich tone, that is appealing to some people, but will be much louder than stock. Not recommended for people who like their car to be quiet.
   
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   High-Flow Exhaust Headers: These are expensive and will add only a small power gain. This is what a person does when they have exhausted other possibilities and are willing to accept a high cost upgrade for a small performance gain. Exhaust headers go well with performance exhaust.
4. 4
   Performance Cams: These are an engine part that will make your car rev up more quickly. These are on the expensive side, and are difficult to install, but work in excellent conjunction with header or exhaust upgrades.
5. 5
   High-Performance Tires: If you're upgrading your car, get some good tires. It doesn't matter how much power you have if you don't get good traction.
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   Turbocharging/Supercharging: This can add up to 25-30% power gains. However, turbocharger kits cost about $3000 for common applications, and go up in price for less common applications. Turbochargers are excellent for any car, anywhere, but can be prohibitively expensive, and are difficult to install.
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   Cold-Air/Ram-Air Intake: This is a simple upgrade that makes your air intake draw in air from a cooler place outside your car. Some cars will benefit greatly, and some will not. Usually, higher-end cars will not be able to benefit from this, as they already have a well-designed air intake system.
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   Engine Swap: Changing the engine out for something stronger. Note that this is an incredibly intensive project, reserved for people building up extremely high-end cars themselves, people who have extensive mechanical knowledge.
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   Weight Reduction: Start with taking all the junk out of your car's trunk. All that stuff is adding weight. Remember that as little as 20 pounds can change how well a car accelerates. You can also go for more expensive weight reduction such as replacing body parts with carbon fiber.
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    Water-Injection: For $300, a good water-injection kit increases gas mileage, power, reduces carbon deposits within the combustion chambers, and prevents engine pinging. Most of the time, having such a system installed will even let you buy lower-octane fuel. Water-injection kits will have almost no performance gains on naturally-aspirated engines, but can help restore lost power. Turbocharged engines will have massive power gains with water-injection.