I think it made a difference on my 2.7 when I installed mine. It was not much faster acceleration but I felt more power in the higher end.
Needless to say, it's beneficial with exhaust modification and is rather loud when you punch it.
Heres a video of when I got mine on, however I did have performance headers too. The sound you hear, though, is all intake, and it really does sound pretty good. The video I took though, with my shitty digital camera, does not give it good justice.
<object width="480" height="385"><param name="movie" value="http://www.youtube.com/v/Zw3qtnf_AUM?fs=1&hl=en_US&color1=0x5d1719&color2=0xcd311b"></param><param name="allowFullScreen" value="true"></param><param name="allowscriptaccess" value="always"></param><embed src="http://www.youtube.com/v/Zw3qtnf_AUM?fs=1&hl=en_US&color1=0x5d1719&color2=0xcd311b" type="application/x-shockwave-flash" allowscriptaccess="always" allowfullscreen="true" width="480" height="385"></embed></object>
I noticed though, the volume of the intake just skyrockets when you get the exhaust done.
<object width="480" height="385"><param name="movie" value="http://www.youtube.com/v/QnxxvKbBXwA?fs=1&hl=en_US&color1=0x5d1719&color2=0xcd311b"></param><param name="allowFullScreen" value="true"></param><param name="allowscriptaccess" value="always"></param><embed src="http://www.youtube.com/v/QnxxvKbBXwA?fs=1&hl=en_US&color1=0x5d1719&color2=0xcd311b" type="application/x-shockwave-flash" allowscriptaccess="always" allowfullscreen="true" width="480" height="385"></embed></object>