Best Subaru to modify

Getting more air into the engine’s combustion chambers produces more power, right? Right. After a simple installation, the low-restriction conical air filter and straight intake tube of the K&N Typhoon kit (800-858-3333; gave us a 17-hp increase at the wheels and a new jolt of torque worth 21 pound-feet. The intake carries its own million-mile warranty and doesn’t void the factory warranty. The downside: It doesn’t meet California emissions regs, and the increased intake noise was hated by the old folks in our office.

STEP 2: The Exhaust Tactic

We put our project car on a dynamometer with the K&N Typhoon intake and the Magnaflow exhaust (the numbers mentioned earlier were achieved with each performance piece installed solo on the WRX). With both installed, horsepower was up by 11 over stock and torque was up 20 pound-feet—increases that are less than those produced by the modified intake alone. The extra airflow on both ends was apparently too much for the factory ECU to cope with, and it compensated by cutting power right when the turbo reached maximum boost. Either the intake or exhaust works fine alone, but ECU modifications are required to get them to work in tandem.

STEP 4: Let’s Get Serious

On The Dyno: Stock vs. Tuned

Waiter, Check Please!

K&N Typhoon kit. $322*
Magnaflow exhaust. $774*
Cobb Tuning AccessPort. $695
Cobb Tuning downpipe. $595
Custom engine tune. $460
Bridgestone Potenza RE-11 tires. $732