^^ you hae to use the "+" and "-" signs in your search. use the '+' before words you WANT mentioned in the post/topic and the '-' before words you do NOT want included in the search.
for instance, if i was searching for a sparco shift knob (for example) i would personally use something that looks like this:
+sparco +knob -seats (since sparco is more known as a seat maker and many threads contain sparco seats--which i am NOT looking for)
that said, here's a link that contains many sound clips of various exhausts (including the greddy evo exhaust) plus dynos and other, condensed information that should be helpful.http://www.turbomagazine.com/tech/0209tur_exhaust/index.html
hope this helps