It is for environment and get engine and catalytic converter to operating temperature ASAP.

On car with twin-out tailpipes. Only one side has the valve. Some have different design but same result is achieved.

The valve from OEM is also vacuum triggered. Aftermarket either wire a button or they give you remote control. Aftermarket is simply for noise because it don't connect to ECU to automate the open/cold logic.

1) During cold start the valve close (engine also run higher RPM, same as other modern car without the valve also)
2) Once car catalytic converter warm up, the valve will open when car is at stop/idle
3) one drive off, the valve close again
4) The valve remains close unless you drive hard or in sport mode

The conventional twin-out tailpipes. My car behave the same as this.
https://youtu.be/KoWdsOt7Q9I

Porsche valves are before enter the muffler. Force the air through high resistance path or straight path. Achieve the same purpose.
https://youtu.be/HvDOndfATc4


I would say it is waste of money in Myvi. Less sound absorption = pure loud noise. The sound tone and note are not nice. No matter mod what exhaust can't make a small CC inline-4 sounds like Inline-6, V8 etc

An old V12 S-class, remove the muffler it sounds exactly like good old V12 F1 car. Signature sound is decided by the engine, not the exhaust. Jump to 6:58.
https://youtu.be/Cankvv99n8A

At least TS is kind enough to put one with valve, can go silent on demand and not disturb people 24x7.

This post has been edited by constant_weight: Nov 20 2021, 12:04 PM

I don't like this response, but it is so damn true about the beng mode 😭

P/S: when beng fetch lian, no need to switch to civilized mode. So might as well just straight pipe and be loud all the time.

This post has been edited by constant_weight: Nov 20 2021, 03:20 PM