But the power's not the whole story. Mazda has increased the redline from 6,800 RPM to 7,500. It's not clear at this point where torque and power peaks are in the rev range, or how these changes affect low-speed drivability, but more revs are almost always a good thing and aren't likely to detract from the roadster's fundamental goodness. Car Watch reports that lighter pistons and connecting rods are fitted to help reduce rotational mass in the 2.0-liter inline-four. Some valvetrain changes were needed to support the higher redline, mainly stiffer valvesprings to prevent valve float. Mazda also changed the shape of the valves and optimized the intake ports to breathe better at higher RPM. The inner diameter of the exhaust ports were increased to flow better through a new muffler better tuned to the engine's new operating range.
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