Performance exhaust button adds HPs or just DBs?

[stumblinhorse]

What do you think? Button adds horsepower or just loud power? Freer flowing that far back in the exhaust?

 

[hardhat]

Just loud power. Exhaust automatically opens up under high load / rpm. I think quiet mode would limit power at high load /rpm if the valves did not open automatically

 

[Bacon392]

I agree with @hardhat. There’s a video from borla about their upcoming exhaust that shows the stock muffler flows 400 CFM when closed and 1100 CFM when open.