The APR 4.0L exhaust timing gear set is designed to increase the engines volumetric efficiency across a wide range of engine speed including above the stock rev-limiter. This is accomplished by improving the exhaust scavenging and increasing the effective compression ratio. Aftermarket exhaust systems will realize even greater gains in volumetric efficiency due to the lower exhaust gas back pressure.

APR has designed a cooler running thermostat system to aid in performance and durability. By keeping the engine temperature 20 degrees cooler, we are able to run closer to MBT (maximum brake torque) without inducing detonation while reducing catalyst temperatures. In addition the inducted air heat transfer is minimized resulting in a greater mass air flow.












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