Pros
A larger diameter downpipe can make a big difference in the way a turbo breaths by increasing power and boost response. This downpipe increased low- and high-end boost response, especially above 5500 rpm. We added 26 ponies to our fleet. This unit has a cast flange and collector that is tig welded to the rest of the piping and has a mirror-polished finish.
Cons
As with most off-road competition pipes, this piece bypasses all of the factory catalytic converters and is not intended for street use. Also, the mouth of the collector is significantly larger than stock and requires tediously modifying the turbo heat shield before it can be reinstalled. Again, not for the novice tuner.
Notes
We noticed inconsistent boost levels throughout the rpm range on the initial pulls. We surmised the stock boost controller and the ECU noticed the unrestricted exhaust and the faster spooling turbo. Since these conditions are atypical, the computer may have retarded timing, richened fuel and reduced boost. The inconsistent boost levels affected the performance and produced lower than expected dyno readings. To counter the irregular boost pressure, we installed a Turbo XS manual boost controller. This solved the boost issues and we were able to get more power out of the engine.
Parts
Stainless-steel downpipe, manual boost controller
Installation Time
90-120 min
Tools
Ratchet; 10mm socket; 6-inch extension; 10-, 12- and 14mm wrench; side-angle cutters, 2mm Allen wrench and zip ties
Temp
Air temp @ 68 Degrees FahrenheitTemperature difference from previous run: +0 Degrees Fahrenheit
| 2000 to 3500 HP range: -3 to 1 | 2000 to 3500 TQ range: -8 to -2 |
| 3500 to 5500 HP range: 0 to 3 | 3500 to 5500 TQ range: -15 to -5 |
| 5500 to redline HP range: 1 to 17 | 5500 to redline TQ range: 2 to 15 |
| Peak HP 256.2 | Peak TQ 231.0 |
| CONCLUSION |
| | HP Level | HP+ | TQ Level | TQ+ |
| Baseline | 212.2 | | 219.1 |
| 1 A'PEXi intake and induction box | 220.9 | 8.7 | 226.6 | 7.5 |
| 2 5Zigen Miracle Fireball exhaust | 229.8 | 8.9 | 236.0 | 9.4 |
| 3 Injen downpipe/TXS boost controller | 256.2 | 26.4 | 231.0 | -5.0 |
| Final | 256.2 | 44.0 | 231.0 | 11.9 |
| BANKROLL |
| 1 A'PEXi intake and induction box | $ 375.00 |
| 2 5Zigen Miracle Fireball exhaust | $ 800.00 |
| 3 Injen Downpipe | $ 425.00 |
| 3 Turbo XS manual boost controller | $ 83.34 |
| MSRP Total | $ 1,683.34 |
ConclusionMost turbocharged cars are bolt-on friendly, especially when the parts help the turbo breathe easier. Intake- and exhaust-related parts usually make power, as we've seen today. Not only did this car baseline higher, it made 44 hp with three bolt-on parts. However, results may vary since vehicles manufactured after 1996 must have an OBD 2 ECU. Subarus have very good computers even though they are temperamental and not terribly forgiving. (The good news is the computer is designed to save the motor from blowing up!) In the hands of a good tuner, these ECUs can be programmed to take full advantage of the bolt-on components and give you that racer's edge!
A'PEXI USA
www.apexi-usa.com
5Zigen USA
www.5zigenusa.com
Injen Technologywww.injen.com
Turbo XS
www.turboxs.com
XS Engineering
www.xs-engineering.com
Tune it. Power is everything
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A'PEXi USA
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Turbo XS
8041 Queenair Dr., Unit 2
Gaithersburg
MD
20879
3-01/-977-4727
www.turboxs.com
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5Zigen USA
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XS Engineering
4030 Palm St. Ste. 303
Fullerton,
C
92835
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Injen Technology
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By Richard Fong
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