Going Faster - Engine and Drivetrain Modifications
Here is your complete guide to getting more horsepower from your WRX motor. These steps are best followed in order, although they don't have to be. Have you got a NON-turbo late-model Impreza? See our Non-Turbo Guide.
The Subaru EJ25 turbo 2.5-liter motor is an amazing high-tech power plant with a huge capacity for increased performance. Straight out of the box, it generates 265 horsepower, but simple bolt-on modifications can increase that to over 400!
To unleash the increased power from your turbo-charged motor, you need to allow the turbocharger to breath more freely, on both the intake and exhaust sides of the motor. Generally, you should start from the ends of the system and work inward. When you have opened up the intake and exhaust as much as you can, you can switch to a larger turbocharger for even more power. Then there are additional ways to add power to the motor, including electronic add-ons. Note that none of these modifications involve taking apart the motor itself – most of these add-ons can be put on by an amateur mechanic.
All horsepower figures in this catalog are measured at the crankshaft (as opposed to at the wheels) unless otherwise noted. Horsepower figures we quote here are approximate; as always, “your mileage may vary.”