• Owner: Kevin Sadamitsu
• Dynamometer Model: HB Speed Dynomite Dynamometer
• Installation: HB Speed
• Accessport Tuning: Jon Drenas
2006 Subaru Impreza WRX
Dyno 1: Baseline
Pros
The '06 Subaru Impreza WRX comes standard with a 2.5-liter boxer engine, eliminating the previous year WRX's 2.0-liter flat-four power plant. The 2.5-liter mill is rated at a factory 230 hp and 235 lb-ft of torque. Other improvements include a quicker steering ratio, standard 17-inch wheels, upgraded four-piston front and two-piston rear brake calipers, and larger discs (11.5-inch diameter in front and 11.3-inch diameter in the rear).
Cons
The '06 Subaru engine doesn't take kindly to major bolt-on modifications beyond the basic intake, exhaust and downpipe without proper fuel/ignition tuning. "The problem is that the ECU is not quite fast enough to pull out timing if the engine knocks hard, which could blow up the motor," states HB Speed owner and tuner Jon Drenas.
Notes
As with any vehicle tested in 2NR, the WRX was given an oil change, spark plug check/replacement and full tank of Shell V-Power before strapping onto the dyno. In stock trim, the WRX delivered 229 hp and 246 lb-ft of torque at 12 psi.
AEM Cold Air Intake System
Pros
The AEM cold air intake uses a mandrel-bent 6061 aluminum inlet pipe attached to a one-piece, four-layer, cotton-gauze air filter for improved airflow. AEM engineered the inlet pipe to specific length and diameter to match the engine's resonance, helping to move more air to the cylinders. Monitoring fuel trim correction factors and all OBD II sensors during R&D created a product that won't lean out the engine and/or throw a check engine light.
Cons
Installing the AEM cold air system requires removal of the bumper in order to remove the factory resonator. Although the process is time-consuming, we found this setback to be of minor inconvenience, knowing our intake would be ingesting healthy dosages of cold air.
Dyno 2
Parts
Intake, filter, hose clamps, hoses, mounting hardware, license plate, sticker
Tools
10-, 12- and 14mm sockets, 10-, 12- and 14mm open ends, ratchet, extension, screwdriver, pliers
Install Time
40 minutes
Notes
With the newly installed intake in place, we forged ahead with our testing, as dyno numbers showed a minor loss in power from 2,100 to 2,800 rpm. We attribute this loss in power bellow 3,000 rpm to the restrictive factory exhaust and downpipe. The intake delivered an increase in mid-range and top-end power with a gain of 5 hp and 5 lb-ft of torque at 4,300 rpm.
DC Sports SCS (Single Canister System Exhaust)
Pros
The DC Sports exhaust system features three-inch, mandrel-bent 304 stainless steel tubing with a single canister muffler for maximum flow, and is finished with a four-inch polished straight-cut tip. With the DC Sports exhaust, you can drive around town with confidence knowing this exhaust system has met the government required 95 dB street-legal limit in noise pollution.
Cons
Removal of the factory exhaust requires plenty of time and patience. Ask for assistance when installing the new exhaust to help speed up the installation process.
Parts
Exhaust, two-piece mid-pipe, nuts and bolts, gaskets, stickers
Tools
12-, 14- and 17mm sockets, 12-, 14-, 17- and 22mm open ends, ratchet, extension, crescent wrench and WD-40.
Installation Time
60 minutes
Dyno 3
Notes
While many exhausts sold on the market today tend to come off as obnoxious noise-makers, the DC Sports unit emits a mild tone that won't require earplugs when driving. But don't be under the presumption that just because this exhaust can fly under the radar at 95 dB or less, it falters in the power department. The DC Sports exhaust made an impressive 6 hp and 16 lb-ft of torque at 3,800 rpm over our previous run, with plenty of gains in the mid range.
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