I've actually seen this done tonight and was searching on the forums how to do it myself. Cruising the CBD in New Orleans and ran up behind another Si and noticed it right away. his was much louder than mine as well (well, not THAT much louder but could tell) but he also told me he had an Injen CAI and that the intake is mostly what was heard.
... but the silencer was definitely off, regardless of whether or not that's what made it sound better or if it was the intake.
