Reduce back pressure in high spinning and high speed driving. (NB. When choice is made of the one under 100cell, initial torque may drop down a bit because torque band shifts backwards.) Special internal design is applied, resulting in 30% higher efficiency than products of other companies for the same volume. We have secured speedy response for acquiring swift engine response and displaying sportier exhaust sound. With the unit controlling engine and exhaust gas smarter getting smarter, engine warning lamp may turn on in extreme conditions, but that is a common symptom even with vehicles having stock catalytic converter and can be easily resolved by ECU reset. Extreme conditions refer to special driving conditions, such as high speed driving and sudden change in humidity and temperature by a sudden change of weather like from heavy rain to sunny brightness.