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/InstallationHeater, Ventilation And Air Conditioning
Abbreviation
AAS
Active Adaptive Shift
ABS
Antilock Brake System
ABDC
After Bottom Dead Center
ACC
Accessories
AFS
Adaptive Front Lighting System
...
Front Seat Belt Removal/Installation
WARNING:
Handling the front seat belt (pre-tensioner seat belt) improperly can accidentally
deploy the pre-tensioner seat belt, which may seriously injure you. Read the
air bag system service warnings and cautions before handling the front seat
belt.
(See AIR BAG SYSTEM SERVICE W ...
Differential Oil Temperature Sensor
Purpose, Function
The differential oil temperature sensor detects the rear differential oil
temperature based on the resistance of the thermistor, and inputs it to the
AWD CM.
Construction
The differential oil temperature sensor is installed in the rear differential
carr ...