With just $1,000 in OEM STI upgrades under the hood, Doug Nelson's Forester XT produces an
According to Doug, the must-have parts to upgrade a XT to STI power under the hood are a STI non-catted up-pipe, a STI intercooler, a STI VF39 turbocharger and a STI axle-back exhaust system (although the front muffler hanger and tailpipes will need to be tweaked for proper fitment), a STI hood scoop from a JDM '02-03 WRX, and if you have an '04 XT you can directly swap in a STI ECU, but later year XTs will need a reflash (and of course a reflash is a good idea anyway if you make some other high performance mods to your XT). An STI fuel pump will work fine, but given how inexpensive a Walbro 255-lph fuel pump is, that's probably the better option because it gives you some room to grow.
The beauty of this upgrade path is that all the parts are easily sourced for around $1,000 from JDM importers and in the "For Sale" forums on popular Subie spots like nasioc.com and iwsti.com or from Doug's favorite shop eastcoastswappers.com.
The surprising part about this pseudo-STI conversion is that it's not only inexpensive but also very effective in the power department. A stock Forester XT produces about 176 hp and 172 ft-lbs of torque on an all-wheel dyno, while an '04 STI generally produces about 235 hp and ft-lbs of torque at the wheels. With the above STI upgrades, Forester XTs generally produce about 260 whp and 300 wtq, making it more powerful than a stock STI. Doug was unsure why XTs make so much power with these simple STI upgrades, but some good theories include better airflow to the air intake because of the larger front grille opening on the Forester, better airflow to the top-mount intercoolerbecause of the shape/angle of the Forester's nose and hood, and perhaps even a less restrictive exhaust path.
With a subtle set of aftermarket wheels, WRX springs for a 3-inch drop and a few STI trim
Since the Forester's chassis is basically the same as an Impreza, The STI treatment doesn't have to end under the hood either. According to Doug, "Any '04-07 WRX or '04 STI spring/strut combo will bolt right up without any problems. Only the '04 STI struts will work with the Forester XT because the hub mounting was changed for 2005. They can be made to fit, but it's not really worth the cost involved. The WRX/STI both use the same-sized front sway bar. Another thing to consider is the fact that Japan has had the Forester STI for some time, and it has a number of cool toys and trim options that are easily sourced. For starters, the trim piece around the radio on JDM models come in a slick flat black. Also offered in Japan is a cool little storage box under the radio that can hold two 16-ounce water bottles." And, of course, there's also the STI badges off a JDM Forester STI and other items that'll bolt right up like STI seats and steering wheel right down to the big Brembo brakes and programmable center differential.
With so many OEM STI upgrades available at a reasonable price and with factory quality and ease of installation, turning the awardwinning '04-08 Forester XT (Car & Driver's Best Small SUV, '04-06) into a seriously quick street machine has a lot of appeal. Can you imagine the look on the face of that mullet-haired Mustang driver who just ate a mouth full of dust from your box-on-wheels cute ute? And with a nice set of aggressively offset wheels and a ride height reduction via '04 STI shocks and springs or an aftermarket coilover setup, a Forester should retain most of its utility (though I doubt many Forester owners ever go off-roading anyway) while achieving a much sportier appearance and far superior handling.