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/InstallationOil Pan Removal/Installation
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 ...
Power Seat Switch Removal/Installation
WARNING:
Handling a side air bag improperly can accidentally operate (deploy) the
air bag, which may seriously injure you. Read the service warnings/cautions
in the Workshop Manual before handling the front seat (side air bag integrated)..
1. Switch the ignition off (LOCK).
2. ...
Cooling System
Outline
Passing water resistance is reduced by improvement of the engine coolant
passage shape.
Pump efficiency is improved by changing the water pump impeller to the closed
impeller.
Structural View
Flow Chart
Structure
Consists of the followi ...