2001 - '07 Subaru Impreza WRX | Tech Tips

David S.
By David S. Wallens
Jun 15, 2022 | Subaru, WRX, Tech Tips, Buyer's Guide, Impreza | Posted in Buyer's Guides | From the Nov. 2015 issue | Never miss an article

[Editor's Note: This article originally ran in the November 2015 issue of Grassroots Motorsports.]

North America never officially received the first-generation Impreza WRX. Instead, we got the second generation model as our first chance to experience the performance of a souped-up Impreza.

Available as both a sedan and a wagon, here's everything you need to know if you are in the market for a GD-chassis Impreza WRX.

Meet Our Expert:

John Marsteller
Mishimoto Automotive
(877) 466-4744

The 2001-’07 GD-chassis WRX has always been a fantastic enthusiast vehicle. Now that prices seem to be plummeting on these second-generation models–likely a result of the recently released 2015 model–the allure of the all-wheel-drive, turbocharged ’Rex is quite strong.

If you need an AWD vehicle for winter snow driftier, driving–this is a pretty nice choice. Additionally, the 2001-’07 model years offer three different body styles–Bugeye, Blobeye, Hawkeye–as well as a wagon option. What’s not to love?

When it comes to going faster, tires are always going to be a first choice for cutting down autocross times. A nice set of Bridgestone RE-71Rs or Dunlop Star Specs on an appropriately lightweight wheel is going to be the best bang-for-your-buck upgrade. Thicker front and rear anti-roll bars and new end links are another easy modification that will make a huge difference by reducing body roll and improving handling.

As for power, basic bolt-on modifications will yield some nice gains with a GD. A downpipe, cat-back exhaust and tune should produce right around 250 wheel horsepower and 280 ft.-lbs. of wheel torque. This is a nice bump over the factory output and can certainly improve the driving experience. 

Be sure the vehicle is up to date on all maintenance to take full advantage of your modifications. Pushing greater power and boost pressure will generate additional heat within the intake system, so make sure your car can handle it. 

A tuning device is also a great base modification that pays dividends as your vehicle evolves. A simple tune will kick up the power a bit and unlock potential for when that downpipe and exhaust arrive at Christmas.

At this point, an intercooler upgrade is not a bad idea to help reduce intake temperatures and get the most from your tune. Mishimoto offers a very efficient direct-fit, top-mount intercooler that provides dyno-proven gains and massive drops in intake temps.

When you’re ready to really dive into the modification process, top-end power should be the first thing you address. The stock TD04 is a tiny turbo and has its limits. If the downpipe/exhaust/tune modifications do not satisfy your hunger for power, a turbocharger upgrade is going to be necessary. The additional airflow will help improve power up top and also reduce intake heat over running the factory turbo at higher boost pressures. This, of course, is a costly investment. 

When it comes to maintenance, a few specific areas require special attention. Wheel bearings are a pretty common failure point for the WRX. As with any wheel bearing, humming and play in the wheel are indicators that something’s wrong.

Numerous failures have been reported regarding the reliability of the factory five-speed transmission. They’re typically a result of increasing power output past 300 horses, animated driving and aggressive launches. Puts a bit of a damper on the ownership experience, doesn’t it? 

Normal driving on a mildly modified example shouldn’t cause any problems with the transmission, but that’s like buying your son a new baseball bat and breaking the news that he’s this season’s designated bunter. Good news, though: The STI six-speed is an easy swap and can handle more abuse.

Another failure we see quite frequently involves the stock radiator end tanks. The factory plastic radiator is not of the best quality and tends to degrade over years of driving. If you have a factory-installed radiator from 2001, it’s probably time for some preventative maintenance. Replacing the stock unit with an aluminum counterpart provides additional durability and improves cooling efficiency. Mishimoto offers both two-row
and three-row aluminum radiator options for the GD, both of which are drop-in replacements.

Subaru flat-four engines of the turbo variety tend to burn some oil–not an incredibly alarming fact, but something to keep in mind during ownership. Factory specs note that normal oil use is up to 1 quart every 1000 miles. This will vary based on numerous factors, of course.

The fenders and subframes are both common areas of concern for rust. Depending on your feelings about aesthetics and your planned use for the vehicle, bodywork concerns may not really impact your purchasing decision. A quick peek underneath the car should reveal any issues with the frame assemblies.

If you’re shopping for one of these WRXs, it’s a good idea to ask the owner about the aforementioned maintenance items and service intervals. Check the maintenance records, too. Subaru recommends timing belt replacement every 105,000 miles, spark plug replacement every 60,000 miles, and fluid exchanges (oil, transmission and differential) regularly. The rod bearings love lubrication and are quick to fail if they run dry.

Another issue for buyers to keep an eye out for: poor modifications. Sketchy workmanship can result in a horrible vehicle ownership experience. (Ask me how I know!) The key is to recognize or ask for a full list of vehicle modifications and begin researching each component. Assuming the modifications are quality pieces and the vehicle is running well, the risk may be worth it. However, in general you want to start with a blank slate if possible.

Meet Our Expert:

Marshall Glasgow
Cobb Tuning
(866) 922-3059

By today’s standards, the factory 227 horsepower is a bit on the low side. To remedy this, a basic Stage 2 setup does wonders for low- and midrange torque as well as overall drivability. 

Power wise, we see a ton of people going with the aforementioned Stage 2 configuration. This consists of an Access port for tuning and an upgraded turbo-back exhaust. As long as the cars are kept in good mechanical condition, this provides a great bump in power over stock without hurting reliability. 

An old trick that used to be popular for WRX owners is the “milk jug mod,” which entails removing the intake silencer in the passenger fender well. Actual power gains are negligible, but the gains in sensory feedback provide an enhanced driving experience. 

The most significant issues we see with these cars usually involve powertrain reliability. The cars are capable of running well for a long time as long as proper maintenance is completed. Ensuring the timing belt and associated pulleys and tensioners have been replaced will also go a long way toward engine reliability. 

Another big issue: wheel bearings. The cars with 5x100mm wheel bolt patterns are notorious for chewing through them when introduced to higher lateral loads. There are companies offering upgraded units that are much better suited for performance driving events. 

If you’re planning on getting your WRX on track, we definitely recommend a more performance-oriented set of tires. Even in stock trim, the WRX is capable of much more than the standard-equipped tires will allow.

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trigun7469 SuperDork
8/6/20 9:37 a.m.

Great article, I have been looking for one for the past 10 years that is reasonable priced and not ratted out. Locally to me they typically have body damage, which can include accident and rust. The drivetrain are usually shot and the modifications are questionable. On top of that they are asking a ridiculous price. Regardless I still can't get the memory out of my head as a young college kid going to the dealership and them throwing the keys to me and let me take it with my friend. We were ripping around the streets and even found a dirt road. It became a fun hobby on the weekends to go on test drivers, back then they would just throw us the keys and we would throw the car around complete a couple J-turns and throw the keys back to the dealership and leave. I guess somethings are fun when they are free to us lolz.

shelbyz Reader
8/6/20 1:55 p.m.

I absolutely loved my 2002 WRX Wagon. Despite driving it like I stole it and owning it from around 145k to 185k, it was one of the more reliable cars I've owned. Probably helped that I didn't mod it past what the article calls "Stage 2". Only I did it super budget with a free canned tune from a buddy with the same year car and a Tactrix cable/adapter, $200 shipped eBay turbo back, a panel filter and a name brand catless up-pipe that cost more than everything else combined. Ran low 14's at my local drag strip with awful 2.5 second 60' foot times from a bad driver mod.

IIRC, at the time I bought it, it was generally thought that for non-STi WRX's you weren't looking to do more than basic bolt ons to, the 2002-04 EJ20 cars were more reliable than the 05-07 cars that jumped up to the EJ25. Also IIRC, the insurance rates for a WRX wagon were a lot cheaper than the sedan.

FWIW, I cross shopped my 2002 against a 2006 WRX Wagon (both bone stock 5-speeds) that had half as many miles and found the 2002 to be more fun to drive. Although I can't remember specifically why that was.

What killed it for me was the city MPG's when 93 octane went over $4/gallon and the corrosion. The fender/quarter rust didn't bother me much, it was stuff like the axles fusing to the hubs and every single part that attaches to the rear knuckle fusing to it or the one huge long bolt that attaches everything to the bottom of it.

If I had to do it again, I'd get one from somewhere that doesn't use salt in the winter.

Fitzauto Dork
8/6/20 2:56 p.m.

My 02 wagon has been a blast. Owned it since 155k and now its on 200k. 

I got lucky in that mine was a one-owner un-modded example. besides the usual high mileage stuff (worn bushings mostly) its never let me down. Only running a "Stage 1" tune with the mentioned airbor silencer delete and a home-brew muffler delete.

Great cars if you want something fun and practical, and insurance is cheap for the wagons.

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