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/InstallationRear Seat Belt Removal/Installation
CAUTION:
The ELR (emergency locking retractor) has a spring that will unwind if the
retractor cover is removed. The spring cannot be rewound by hand. If this occurs,
the ELR will not work properly. Therefore, do not disassemble the retractor.
1. Remove the following parts:
a. T ...
Crankshaft Pulley
Purpose, Function
The crankshaft pulley transmits the drive force to the auxiliary parts via
the drive belt.
The crankshaft pulley suppresses torsional vibration of the crankshaft.
Construction
The crankshaft pulley is installed to the front of the crankshaft.
...
Seat Belt Precautions
Seat belts help to decrease the possibility of severe injury during accidents
and sudden stops. Mazda recommends that the driver and all passengers always wear
seat belts.
All of the seat belt retractors are designed to keep the lap/shoulder belts out
of the way when not in use.
The driver ...