For example, a cold air intake system, like the chrome tube shown below, will allow colder air into the engine, and more of it, producing more power and better gas mileage.

Exhaust upgrades, such as performance headers, catalytic converters, and free-flow mufflers will also increase horsepower, and will add a nice race-car-type sound to your vehicle!

There are lots of other things you can do to create more horsepower in your ride, but these are the basics that most people start with. Real horsepower junkies will go for superchargers or turbo kits, which are expensive and usually require other modifications to the engine to run properly and reliably.