good reading on this post. The "snorkle" is from what I can feel and hear on my 2000 S is definitely a mod one needs to do for what ever reason. Now some data on added hp. There seem to be the question on how to do this. well here's the link.
http://www.ppbb.com/boards/ppbbphp/showthreaded.php?Cat=&Board=ARCHIVES&Number=820409&page=&view=&sb=&o=
One might have a calibrated body to feel the gain but you sure can hear the change from doing the mod.
Ben