NotesHayward & Scott has made a strong presence in the U.K. and has 20 years of experience. The Basildon, England-based company has finally made its way to the States. Its first product is a 3-inch performance exhaust system for the WRX. This unit is entirely hand-made using stainless steel with laser-cut flanges and is professionally hand-welded.
TemperatureAir temperature: 83.7 degrees FahrenheitTemperature difference from previous run: +0.5 degrees Fahrenheit
Tools14mm combination wrench, 10- and 14mm socket, ratchet and WD-40
Dyno 4APS SR375Dual-EntryTop-Mount Intercooler342.8 HP 409.0 tq
ProsComing in at nearly 2.6 times the volume of the factory intercooler, the APS top-mount intercooler has a frontal area measuring in at 20.7x7.5x4.5 inches while the factory STi is sized at 18.5x7x3.5 inches. Claimed to have less than 0.02bar (0.3 psi) of pressure drop at 320 hp across the intercooler, the APS top-mount intercooler sports a dual-entry top mount with twin inductions to better spread the cooling effect on the incoming charge.
PartsIntercooler assembly, APS one-piece cast compressor discharge duct, two gaskets and bracket
| 2000 to 3500 HP range: -1 to 24 | 2000 to 3500 TQ range: -1 to 96 |
| 3500 to 5500 HP range: 24 to 0 | 3500 to 5500 TQ range: 96 to -8 |
| 5500 to red line HP range: -7 to -11 | 5500 to red line TQ range: -5 to 0 |
| Peak HP 342.8 | Peak TQ 409.0 |
| CONCLUSION |
| | HP Level | HP+ | TQ Level | TQ+ |
| Baseline | 332.0 | | 341.5 | |
| EcuTeK custom programming | 329.9 | -2.1 | 375.8 | 34.3 |
| Hayward & Scott exhaust | 339.0 | 9.1 | 385.7 | 9.9 |
| APS top-mount intercooler | 342.8 | 3.8 | 409.0 | 23.3 |
| Final | 342.8 | 10.8 | 409.0 | 67.5 |
| BANKROLL |
| EcuTeK license and custom programming | $ 750.00 |
| Hayward & Scott stainless-steel exhaust | $ TBD |
| APS SR375 top-mount intercooler | $ 115.00 |
ConsWe encountered some minor fitment problems when bolting up the factory blow-off valve. The base of the unit was coming in contact with the intercooler, causing a leak and high-pitched whistling sound when in boost. After locating the culprit, we added an extra blow-off gasket to quickly solve the problem.
installation time45 minutes
ToolsRatchet, 10- and 12mm sockets, extension, screwdriver and pliers
NotesThe APS vs. STi intercooler showdown was no contest as the larger, aftermarket intercooler and efficient fin design kept a lower temperature throughout the dyno session. At 3600 rpm and again higher in the band we encountered severe detonation using the factory intercooler. The heavily heat-soaked STi unit forced us to back off ignition timing and re-adjust fuel tables with the EcuTek unit. Goes to show size does matter!
TemperatureAir temperature: 84.1 degrees FahrenheitTemperature difference from previous run: +0.4 degrees Fahrenheit
ConclusionWe can't stress enough the importance of fuel management tuning with every component installed on your vehicle. Fuel tuning and ignition mapping become critical whenever you install aftermarket components on newer vehicles with complex ECUs and OBD-II systems. Although the horsepower figures came in at a modest 10.8-hp gain, the monster 67.5 lb-ft of torque we gained is enough to put a smile on any STi owner's face.
Sources
Air Power System (APS)www.AirPowerSystems.com
Crawford Performancewww.CrawfordPerformance.com
EcuTeK Performance ECUwww.EcuTek.com
Hayward & Scott www.HaywardandScott.com
I-Speedwww.I-Speed.us
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Air Power System (APS)
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Hayward & Scott
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Crawford Performance
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I-Speed
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EcuTeK Performance ECU
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