So my STOCK Civic is lower than the legal limit in Texas.

[Isaac Zachary]

Originally Posted by cRiPpLe_rOoStEr

Most likely it will be locked or unlocked on-demand, yet I'm not so sure.

I found this article:

https://www.thedrive.com/news/45026/...-exhaust-pipes

"Above a certain engine rpm, there is a valve. So they open that and it goes straight to the outside of the car, which reduces the backpressure and achieves the 300 horsepower."

[freebeard]

It's nothing new

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Exhaust Cutouts | Summit Racing
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[aerohead]

Originally Posted by Isaac Zachary

I wonder if the new Toyota Corolla GR will have a similar issue as its exhaust has a solenoid actuated valve to bypass a major part of the muffler. I'm not sure what makes it open though, but IIRC it's when you floor it.

The modern Corvettes run on four cylinders, with half the exhaust closed off until you spank the go-pedal. Then the computer picks up on the prompt, and everything reconfigures for high-output, low restriction.
Some motorcycles have done this for decades.

[cRiPpLe_rOoStEr]

Originally Posted by aerohead

Some motorcycles have done this for decades.

I don't remember this, as EFI took way longer to catch up on motorcycles than on cars.