What Is a Muffler

....
Playing With Language:

Dictionary says; A muffler is a device for reducing
the amount of noise emitted by the exhaust of an
internal combustion engine.

The ad says; The Flowmaster Outlaw Series Race Mufflers ....
These race mufflers are designed to be used at race tracks
requiring mufflers, but without dB restrictions.

Without dB restrictions. Ain't dB's noise? Go figure.