The 4A-FE is different from the 4A-GE in terms of performance and power. Although both have the same displacement and are DOHC, they were optimized for different uses. The first obvious difference are the valves, the engine's intake and exhaust valves were placed 22.3° apart (compared to 50° in the G-Engines). The second is that it employed a "slave cam system", the camshafts being geared together and driven off one camshaft's sprocket (both camshafts' sprockets on the G-Engine are rotated by the timing belt). Some of the less directly visible differences were poorly shaped ports in the earlier versions, a slow burning combustion chamber with heavily shrouded valves, less aggressive camshaft profiles, ports of a small cross sectional area, a very restrictive intake manifold with long runners joined to a small displacement plenum and other changes. Even though the valve angle is closer to what is considered in some racing circles to be ideal for power (approximately 25 degrees), its other design differences and the intake which is tuned for a primary harmonic resonance at low RPM means that it has about 10% less power compared to the 4A-GE engine. This engine design improves fuel efficiency and torque, but compromises power. Power rating varied from in the US market. Late-model engines are rumored to make slightly greater power but still received a rating.