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/InstallationTcs Control
Outline
The TCS control actuates torque reduction through engine control, as well
as using brake control to control traction.
NOTE:
Engine control: Engine output is lowered by fuel cut and ignition timing
control to reduce the traction, preventing driving wheel slip.
...
Cargo Compartment Light Bulb Removal/Installation
1. Disconnect the negative battery cable..
CAUTION:
Always disconnect the negative battery cable before performing the cargo
compartment light bulb removal. Otherwise, the circuit may be shorted resulting
in damage to the related parts such as the rear body control module (RBCM).
...
Rear Stabilizer Control Link Inspection
1. Remove the rear stabilizer control link..
2. Inspect for bending or damage. If there is any malfunction, replace the rear
stabilizer control link.
3. Rotate the ball joint stud 10 times and shake it side to side 10
times.
4. Measure the ball-joint rotational torque using an Allen wrench ...