Rear silencer with flap EXHAUST for F82-M4 vol.2

This is the second part of the BMW F82-M4 exhaust development.
We made a rear silencer with flap similar to stock.
The stock exhaust flap actuator is used, so the operation depends on the stock.
The flap is made by LAPTORR and has a larger outer diameter than the stock.
When the flap is open, the main pipe diameter is larger, so the exhaust flow is better and can handle higher boost.
When the flap is closed, the exhaust is routed through the rear silencer, which is quieter than the stock silencer.
Next, we will try to design a rear silencer structure that is quiet and has good exhaust flow.