Installing certain engine upgrades can help net a few more horses out of your pony car, no matter which year or engine size. Before the addition of any power increasing components, however, check the local ordinances and emissions laws to ensure your upgrades are in compliance. Many times, older Mustangs do not apply, but models from the mid-1970s on might be questionable in certain areas.
Put a performance camshaft into the engine. In most V8 applications, a mild camshaft will add 20 to 30 horsepower, and it goes up from there with more extreme cams. Recommended are previous engine repair and tear-down techniques, because the entire front of the engine as well as the radiator and front grille will have to be removed for this step. The camshaft will likely come with installation instructions, but a working knowledge of how they operate is a big plus.
Install headers in place of the stock exhaust manifold. It has long been known that the factory exhaust manifolds hamper the power-making process, and so the addition of a good header system will free up a lot of power. In a V8 application, expect a real world 10 to 30 horsepower gain, depending on the headers and the condition of the engine. For this step, simple hand tools are likely all that will be necessary, but, for some systems, welding is a plus. Many times the catalytic converter will need to be welded back into place, for example. Older models simply connect via the flanges.
Install nitrous-oxide nozzles into the fuel system. Nitrous-oxide systems (or NOS) have long been used to boost power in a big way. A stock V8 engine can normally withstand a 200 horsepower shot without failing. A 100- or 150-horsepower NOS system will provide reliable power for years to come, no matter what the application.
Install a power chip. While this modification only applies to Mustangs with on-board computer systems, it can definitely increase the horsepower. The install is simple and quick, and the racing chips do not usually cost an exorbitant amount. They reconfigure the computer to give the engine more power through components such as fuel delivery and timing.
Install a lower (higher numerically) ring and pinion gear set into the rear end. While this will not net the car any more actual horsepower, it will cause the Mustang to become faster. For instance, if the current gearing in the differential is 3.07, upgrading to 4.11 gears will result in the car taking off and reaching speed much quicker because of the new ratio.
