Abstract: An accessory to an exhaust system is disclosed which reduces the decibel output from the engine of a vehicle while negligibly affecting the horsepower produced by the engine. The accessory can be built directly into an exhaust system by the manufacturer or added as an after-market enhancement by the consumer. The key elements to the device include a sound-funneling housing which circumscribes a diffusing element, both of which are removably or permanently capped on one side. The uncapped end of the housing is formed to engage a portion of the actual exhaust system. The overall result of this device reduces the total amount of noise produced, without noticeably affecting engine performance, while simultaneously inhibiting harmonic sound waves that can create an annoying rattling sound for the driver or passenger.