The change in sound is pretty subtle. The only time you really notice it is from the OUTSIDE when the engine's cold. I sounds a little mechanical; but once ithe engine/exhaust is warmed up, the sound is just a little deeper. My wifes only noticed it after I mentioned it to her. It's not a huge difference.

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2003 4.6is, Saphire Black on Black with Aluminum trim, Comfot Seats, Loading floor, Nav, TVonNav, Focal Utopia's in front, with Rainbow's in back, Helix 5 channel amp. ACS pedals, Aluminum steering wheel trim, X-pipe