I ran an AFE Stage II on my truck for a few months and though it was a good filter, it was just loud to the point of being annoying. My dad has been running a K&N on his 99' ever since he had it pretty much, so I went with what that. Been running the K&N Cold air for about a month and a half...performance didn't go down at all, filtration is basically the same and the turbo is still loud, but nothing like that AFE...dang thing was loud enough to hear over my speakers if you listened for it. I read a post in here about a bunch of people bashing the K&N a while back, saying that it was allowing debris and oil, etc. into the tubing and ultimately into the turbo...well, mine is running clean and my father is still ALL stock on his 99' with 450+K miles on his Cummins and has never had a problem either...and recharging is a breeze...simply spray on cleaner, wait a few minutes, rinse wait a bit to dry, spray on a couple thin coats of oil, wait 20 minutes and re-install...piece of cake.

Derek