Also of note is the fairly large top-mount, air-to-air intercooler, which helps further decrease intake temperatures and, combined with DISI, significantly reduces any knock that may be introduced by the K04 turbo. The medium-frame turbocharger features a water-cooled center section and an Inconel shaft. The size of the K04 appears to be appropriate for the 2.3-liter, but after looking at compressor maps we're somewhat speculative on whether or not the boost can be turned up at all without generating significant heat. No matter though, there are already several compressor and complete turbocharger upgrades offered for the 3, but we're getting ahead of ourselves.

The Drivetrain
The six-speed transmission here is the same as the more grown-up Mazdaspeed6 and is partially what contributes to the Mazdaspeed3's stellar gas mileage, despite how much torque the engine seems to continually put down. Gear ratios err on the wide side, but seem to work in light of the flat and generous power curve. Torque steer is generally a problem with FWD cars pushing such power-to-weight ratios. To increase the threshold, Mazda engineers outfitted the five-door with equal length halfshafts and a cone-type LSD, in lieu of a more aggressive Torsen or mechanical clutch type, which also assists in keeping the tires from going up in smoke in first and second gear. Shifting the six-speed is rather effortless, in part due to its triple- and double-cone synchronizers for first through third and fourth gears, respectively. Perhaps the only complaint we have is the clutch, which tends to feel a bit snappy at first but becomes less of an issue as time passes.

Suspension and Brakes
Like the Mazda3, MacPherson struts occupy the front and a multi-link suspension out back. There's 60 percent more roll stiffness here in comparison to the lesser Mazda in part because of stiffer spring rates and larger diameter anti-roll bars at both ends. Compression and rebound rates are also increased by a factor of six times at low piston speeds and 1.3 times at higher ones. The new suspension places the Mazdaspeed3 10mm lower than the Mazda3. Mazda also beefed up the chassis with reinforcements surrounding the front strut towers and throughout body panels. The results make for noticeably less body roll and reduced understeer in comparison to the base Mazda3 and exhibits handling characteristics more on par with something four-legged. Of course, douse the road with a bit of water and we're quite sure WRXs and EVOs would plow right by. Larger-than-Mazda3 four-wheel disc brakes sit at the corners but the Mazdaspeed3 also benefits from a larger master cylinder, which affords more fluid displacement for better stopping. Late braking is no problem here.

Everything Else
The outside is just as functional and quite a contrast in comparison to the base car. Besides its 18-inch rims, a more aerodynamic front bumper and restyled hood and rear wing are fitted to the Mazda, as are a number of under-body aero pieces designed to increase high-speed stability. They're not just for looks. Mazdaspeed engineers wind-tunnel tested such components to ensure their functionality. The Mazdaspeed3's quick - it can cross the quarter-mile in just a tenth or so over 14 seconds; it's fast - it'll do 155 mph, so Mazda says, though we're often hard pressed to get the opportunity to go half that fast here. It's highly communicative-meaning we just point or press and turning and stopping occurs on a whim; it's also priced below $23K. No wonder we like this car. What else is there to say? We just weren't all that happy when it came time to return the keys.

SOURCE
Do It Dyno Performance Center Mazda