Purpose, Function
By lengthening the exhaust passage, the transmission of exhaust pressure waves to other cylinders can be delayed, and the amount of gas exhausted from a cylinder and forced back inside the combustion chamber is reduced By reducing the residual gas, the temperature inside the combustion chamber is reduced and the occurrence of knocking even at a high compression ratio is inhibited.
Construction
The exhaust manifold is installed to the rear of the engine. In addition, the catalytic converter (WU-TWC) is integrated (WU-TWC).

When the No.1 cylinder is at the intake stroke, the No.3 cylinder is at the exhaust stroke. By inducing the high temperature gas exhausted from the No.3 cylinder into the No.1 cylinder, the high temperature gas in the No.1 cylinder remains. If the amount of residual gas is high, the temperature in the combustion chamber rises and knocking can easily occur. With the 4-2-1 exhaust system, the transmission of exhaust pressure waves between each cylinder is delayed by the long exhaust pipes.

Exhaust System Removal/InstallationAwd Control Module
Purpose, Function
The AWD CM calculates the optimal amount of torque distribution for the rear
wheels and outputs a corresponding electric current to the electronic control
coupling (AWD solenoid). This calculation is based on the accelerator pedal
angle, four-wheel speed, engine spe ...
Shift Control Module Removal/Installation [C66 M R]
Removal
1. Shift the shift lever to the neutral position.
2. Remove the plug hole plate..
3. Disconnect the negative battery cable..
4. Remove the air cleaner and air hose as a single unit..
5. Remove the battery and battery tray..
6. Disconnect the control cable from the transaxle.
a. ...
Auto Dimming Mirror Removal/Installation
1. Disconnect the negative battery cable..
2. Remove the screw B.
3. Remove the auto-dimming mirror in the direction of arrow (1) shown in the
figure.
4. Detach tabs while push the cover No.2 in the direction of the arrow (2) shown
in the figure, then remove the cover No.2 in the d ...