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/InstallationSeat Weight Sensor Calibration [Two Step Deployment Control System]
CAUTION:
If any of the following work is performed, perform the seat weight sensor
calibration using the M-MDS.
Replacement with a new seat weight sensor
Replacement with a new seat weight sensor control module
Replacement with new passenger-side seat pa ...
General Procedures (Steering)
WARNING:
Always inspect the steering component carefully for any shock or impact which
may have occurred during a collision or servicing operation. If a damaged part
or a part suspected of being damaged is used, it could result in an unexpected
accident due to the steering mechanism ...
Oil Pressure Inspection
WARNING:
Hot engines and engine oil can cause severe burns. Turn off the engine and
wait until it and the engine oil have cooled.
A vehicle that is lifted but not securely supported on safety stands is dangerous.
It can slip or fall, causing death or serious injury. Never work ...