Coming Attractions
With our part one and part two buildup, we’ve increased the output of the STi by 18 percent or an increase of 46.6 horsepower at the wheels over stock. More power is going to require more boost pressure. To achieve more boost pressure safely, we’ll be evaluating and possibly upgrading the Mass Air Flow sensor, injectors and fuel pump. To make these higher flow items deliver the proper air-fuel and timing curves, a complete “reflash” of the factory ECU will be required. We are hoping that our local tuner, XS Engineering, will have the necessary hardware and software to get our STi in tune. These modifications, along with an upgrade of the factory clutch, should put us close to reaching our Stage 1 goal of maximum power with the factory engine and turbocharger.
The Bottom Line
| HP Level | HP Increase | % Increase | Total | |
|---|---|---|---|---|
| Stage 1 BASELINE | 280.0 | – | – | – |
| Test 1 Perrin + Helix | 298.1 | 18.1 | 6.5% | 18.1 |
| Test 2 A’PEXi SGS | 306.6 | 8.5 | 9.5% | 26.6 |
| * * * * * | ||||
| FINAL POWER | 306.6 | – | 9.5% | 26.6 |