There is a replacement for displacement. Turbochargers have become the great equalizer for smaller-displacement engines. Today, it is common to see small-displacement, turbocharged engines producing the power and torque levels of engines two or three times the displacement. This is the legacy of technology.

Subaru reinvented the outlook of turbocharged four-door sedans when it released the WRX stateside in 2002. Combining the technology of turbocharging with all wheel drive resulted in a capable performance platform.

The EJ205 2.0-liter, four-cylinder boxer engine generated 227 horsepower and 217 lb-ft of torque from the factory. While admirable, many WRX owners noted the lack of top-end power. In this Test & Tune session, we focused on not only increasing peak power, but also addressing the power drop off after 5,500 RPM.

The Players

Proper preventive maintenance is not only crucial to engine longevity but also to peak power production. This 2004 WRX was purchased used and the previous vehicle maintenance records were not available to review. To take no chances, we would treat the WRX to a simple tuneup before installing a piggyback fuel computer and turbo-back exhaust system.

To light the fire in the combustion chamber, we selected NGK BKR7EIX Iridium spark plugs. The small-diameter-center-electrode design of these plugs requires less arc-over voltage to initiate a spark. As a result, misfires under high-load conditions are dramatically reduced and horsepower is maximized.

A simple oil change service on the engine and rearend can increase power at the flywheel as the power lost to friction in the engine and rearend is reduced when well-engineered synthetic performance lubricants are used. Eneos 5W-30 synthetic fluid engine oil and 75W-90 Eneos gear oil provide a 100-percent synthetic base oil that's fortified with an additive package formulated for peak performance and protection.

Since the easiest way to make more power on a turbocharged engine is to raise the boost while maintaining proper air-fuel ratios, the Dynojet CMD piggy-back fuel computer seemed a logical choice. The CMD is Dynojet's newest piggy-back fuel computer (see page 42 for the Quick Test feature on the CMD). By intercepting the factory sensor and driver signals, the CMD is capable of controlling both boost and injector duty cycle. The CMD software allows for data logging and real-time fuel tuning. To get enthusiasts closer to a fine tune, Dynojet will soon be offering staged base programs available for download on the company's website.

With turbocharged engines, reducing exhaust backpressure with a better flowing exhaust system improved boost response and power output. The GReddy Comp Ti-C turbo-back exhaust system features 80mm polished stainless-steel piping. A highly-polished stainless-steel muffler showcases a heat-treated titanium tip and a removable silencer. As expected, the GReddy Comp Ti-C exhaust system includes all the necessary hardware and gaskets for a complete install.

The Dyno

Strapped to the 424xLC four-wheel Dynojet chassis dyno, our 2004 Subaru WRX generated 192.7 wheel horsepower. Using our standard conversion to flywheel horsepower (assuming a 15-percent loss), we calculated the flywheel horsepower to be dead on at the factory-rated 227 horsepower.

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