The story: I have a turbocharged 2l engine in my car, and a 3" straight through exhaust, that is very very loud and drones.
So, I bought a cable operated inline butterfly valve, that can be opened and closed and install between the test pipe and mid-pipe.
Obviously, for me to be able to drive around, I need to drill holes so that when it's fully closed, I could still drive around.
Question is: Should I drill a bunch of little holes, or one larger one. How large should it be for optimal sound?
I am looking to remove the drone(deeper tones) and eliminate sound as much as possible, while still keeping the car at least 50% efficient when closed.
Stock exhaust is 2.5" in diameter and does a fantastic job quieting the exhaust, but it also has a resonator and pretty restrictive muffler.