just installed mine this afternoon too. no whistling on mine either...just some typical breathing sounds when I get on it. I totally dig it so far. I actually thought they did a pretty good job with the instructions too...although, I can't recall if I went step by step or not. I usually only use those things for a guide anyway
oh! I also got K&N's dry charger cover for their filter to protect it from any moisture that may make it's way to the filter. i dig it so far too!