About factory exhaust
The original exhaust system is used by manufacturers for repeated testing, vehicle dynamic performance, environmental performance and fuel economy and production costs and other aspects of product design is considered, and the vehicle powertrain collocation is more reasonable, especially for the weak power of small cars, the original factory exhaust usually not too smooth, but this kind of design instead of optimizing the characteristics of small displacement engine itself low torque is insufficient, the appropriate exhaust back pressure will produce a resonance effect, can improve the efficiency of the exhaust under low speed, more suitable for city road use.

Sound is not proportional to horse power
Some junior riders think the bigger the sound, the greater the horsepower, which is the wrong idea. Therefore, it is absolutely impossible to change the tail section to make the power output increase obviously. For the exhaust system, the main function of the muffler is the exhaust tail section and the middle section, especially the tail section, the role of the muffler is more important. So now the market of the straight tail section, you can get great exhaust noise, but the engine power output is almost never been much change.

The thicker the exhaust pipe, the better the exhaust return pressure is, and the understanding is not correct
In the modified exhaust system need to take into account the power output characteristics of the vehicle itself and their driving habits, to feel the torque output of the low speed is not ideal of the owners, modification of the exhaust is not a good choice. Because retrofit exhaust basically aims at the performance optimization of medium and high speed areas, this modification usually comes at the expense of partial low torque.