The 04 has the new face to it, offers a sun roof, has available heated seats (shaped a bit differant) and offers a black interior in addition to the previous standard blue/black interior. So, unless you want heated seats in California or need a sunroof, the only big change is the exterior.
(And I'd advise against putting in an aftermarket sunroof because aftermarket installers need to cut through one of the roof supports that extends from the B-pillar. This will lower the rigidity of the car and effect handleing. Because of this, the factory sunroof is small so that they don't have to cut.)
That is crap you couldn't take the car over 4000 rpm! The car comes alive after 3000 rpm. I would never buy a car if the salesperson went on the test drive with me... but that's another thread. With a few cheaps mods, the car comes alive at an even lower rpm and rev's so fast, you'll whip right by 3000rpm in no time.
Since the WRX has a factory turbo, its engine was given a fairly low compression ratio (better for turbo cars). This makes the car safer to boost, but also lowers output when the turbo isn't spooling up.
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Brad B.