I wonder if it would make a difference as to what exhaust system and engine mods were done. It doesn't seem like getting more air in would help if you couldn't get it out? Not sure of this, just seems like that is what I have always read.

 

Still I am amazed that after a year of running my heavy breather that the filter element still has that new pink look and is clean as a whistle. I ride in manhattan/long island and it's as dirty as it gets. if the paper element is clean then ther sock grabs air and lets a"small" amount of clean air in. Without the sock unrestricted clean/dirty air would enter, leaving the filter paper dirty in no time at all.