Hey ive seen several times on here that a plenum spacer will increase loudness under the hood... yet today at SpeedSouth the guy told me that a plenum spacer will not change any sound at all under the hood.... which is true?

And im not talking about a spacer with a MREV.. im only talking about a spacer

 

They spacer will five it a deeper tone and not necessarily louder (maybe a little louder but that's it)

 

In the sound clips posted here you can hear that the engine sounds "deeper" in tone (listen to clip 2 vs 3). (You should also consider that the intake was installed at the same time in those sound clips.)