[calbert1999]

Originally Posted by Dragoneye

The ZL1 uses GM's proprietary dual-mode exhaust system. The only other vehicle I'm aware of that features this neat piece of tech is the Corvette. In fact, the Z06 and ZR1 come standard with this system...so that's what you've heard.

Basically, there is a single muffler with two routes for the exhaust to take. One is actually muffled, and the other is as straight through as you can get from the factory. It's a wisper away from being as loud and crazy as if there were no mufflers at all.

So, it sounds "tame" (which is a misleading word with regards to the ZL1...) when idling, or cruising down the highway. This is to control drone and drive-by volume, etc...

But when you step on it, or when it's intially turned on...there are butterfly valves in two of the tips (one on each side, which is why there are four total) that open up and allow the exhaust to take the most free-flowing path, the straight section. This frees up horsepower, and of course, volume.

Not sure which one it would more closely resemble but sounds like a similar approach as diverters or cutouts. Isn't there a feature in the Vettes that has a control that allows you to open close the valves?