Let's talk about automotive performance. This term means a lot of things to a lot of people... from better handling, more speed, more off-road or track capability or even better fuel economy. For the purposes of this list, performance means one thing; getting where you are going sooner. Consider the following top pick performance upgrades if you want to put more power to the ground:
Cold-air Intake - Factory air boxes are restrictive and are usually more about packaging under the hood than feeding your engine much-needed air. A less restrictive intake is an instant power adder.
Bigger Throttle-body - The intake feeds the throttle body, the modern equivalent of the carburetor. The more air and fuel you can stuff into the engine the more power you can make. A higher CFM throttle-body allows more air to pass through your engine.
Forced Induction - Turbos and Superchargers essentially have the same purpose; to stuff more air into your engine by creating pressure. Whether you create pressure with a belt, like a supercharger, or by turning a turbine with exhaust gas like a turbo, the end result is the same. Big power.
Controllers - Your onboard computers have a lot of extra power locked up by the manufacturer. You can free up this extra power with a "chip" or power programmer. With a programmer, you can also change transmission shift points, fuel injection curves and other parameters that return better performance as well as deriving telemetry information for fine-tuning your results.
Free flow exhaust - You get more power from pushing more air into your engine, but if you can't get rid of the exhaust, you can't make room for the next air and fuel charge. Free flowing exhaust systems get rid of the old, burnt stuff to make room for the new stuff. Simple physics for big power.
Better Grip - As the saying goes, "smoke ain't speed." If you are going to make big power you have to get it to the ground or all you will do is make a bunch of tire smoke while sitting stock still. With every power upgrade you settle on, make sure you have the matching rubber to get it to the road.
Potent power can be just an upgrade away and there are many products on the market to help you get the horsepower and torque you are looking for. Start with this list to get the most bang-for-the-buck right out of the box.